Beef and Wheat Berry Sliders with Feta, Caramelized Onions, Baby Spinach and Mint Mayo

There are few more quintessentially American dishes than the good old hamburger. Like its cousin the frankfurter, its name belies origins in Germany that food historians still can not definitively verify. We do know that Louis Lassen, the owner of Louis’ Lunch in New Haven, CT, began selling hamburgers sandwiched between two thick slices of toast in 1900. This turn-of-the-century meal, recognized by the Library of Congress as being the United State’s first official “hamburger and steak sandwich,” became so popular that numerous others have stepped forward to challenge the title…though none has borne the burden of proof needed to unseat Louis.

The hamburger’s little brother, the slider, has even cloudier origins. We know it as a mini burger, nestled in a mini bun. And though the term now generally applies to any diminutive sandwich served up on a “bun-ette” — from crab cakes to sloppy joes — speculation is that sliders began their life aboard Navy ships that, when pitching and yawing at sea, sent burgers “sliding” in their own grease across the galley grill. Were it not, however, for the White Castle hamburger chain, the general public may never have begun associating the term “slider” with small burgers. For some folks I know, a slider will forever be White Castle’s Original Slider®, sold four-to-an-order, with nary a slice of cheese.

So I beg forgiveness from those ardent White Castle fans because The Stout Sprout sliders bare little in common with White Castle fast food burgers. We have the beef, but we brought some whole grain to the party too in order to up the fiber and nutritional content of America’s favorite food. We also put a Greek spin on our sliders by topping them with caramelized onions, sautéed baby spinach, crumbled feta cheese and a smear of mint mayo.

This Greek-American slider is packed with whole grains and fresh tastes

This Greek-American slider is packed with whole grains and fresh tastes

These sliders have a distinctly more adult appeal, but that didn’t stop our Stout Sprouts from helping to make them, or eating them. Predictably, they steered away from the more “gourmet” touches like the mint mayo, but I’m certain that they didn’t know what they were missing.


The Stout Sprouts found lots of ways to help when making sliders

The Stout Sprouts found lots of ways to help when making sliders

Though the below recipe looks like it has a lot of steps many can be done up to a day ahead of time, from cooking the wheat berries, to caramelizing the onions, to making the mint mayo. Once you get going, this is actually a pretty quick dish to pull together.

Wheat berries, if you’ve never used them, are the entire kernel of wheat minus the hull. If they were to be ground down, they would end up as whole wheat flour. They have all the great things that can be found in the whole kernel including the wheat germ and wheat bran and pack a nutritional punch with loads of fiber, protein, iron and vitamin B.

By using a fairly fatty ground beef (85% lean) and searing these sliders to a medium-rare, they have a pleasantly beefy taste that is complemented by the nuttiness of the wheat berries. The wheat berries in this recipe are chewy but tender, having been toasted and then cooked much as you’d cook rice before being added to the beef. They blend nicely with the ground beef and parsley, adding a deeper dimension and texture to these sliders. Paired with feta, caramelized onions, baby spinach and mint mayo, these sliders bring something unique to the dinner table that just can’t be matched by a drive-through.

Wheat berries and parsley marry nicely with the beef in these feta, caramelized onion, baby spinach and mint mayo sliders

Wheat berries and parsley marry nicely with the beef in these feta, caramelized onion, baby spinach and mint mayo sliders

I hope you’ll give these a try, whether you’re looking for new ways to reinvent old recipes, or just want to experiment with whole grains without straying too far from familiar tastes. And now that it’s spring, mint and baby spinach will be popping up all over, bringing lots of seasonal touches to this addictive burger combo.

Beef and Wheat Berry Sliders with Feta, Caramelized Onions, Baby Spinach and Mint Mayo

Ingredients for sliders:
1/4 cup wheat berries
3/4 cup water
1 teaspoon olive oil
Pinch of Kosher salt
1/4 cup finely-diced parsley
1 1/2 pounds (24 ounces) ground beef, preferably 85% lean
1 garlic clove, minced
Additional Kosher salt and fresh ground pepper, to season
A package of small dinner rolls (snowflake rolls) or 9 small crusty bakery rolls (sourdough rolls are especially good, though you could go whole wheat and really amp up the fiber!). Split the rolls before using.

Ingredients for mint mayo:
1 cup loosely packed fresh mint leaves
1 cup prepared mayonnaise
1 garlic clove, minced
1 teaspoon apple cider vinegar
A generous pinch Kosher salt

1 cup crumbled feta cheese
1 onion, thinly sliced and sautéed over medium heat in 1 tablespoon olive oil and a pinch of Kosher salt until caramelized (this will take approximately 30 minutes and can be done ahead)
Lightly sautéed baby spinach or fresh iceberg lettuce leaves, washed and dried and torn into roll-size pieces

Begin by toasting the wheat berries in a dry skillet over medium-high heat for approximately 5 minutes to give them a nutty flavor. Shake the skillet frequently to redistribute the wheat berries and keep them from burning, and use a mesh spatter guard or loose-fitting lid to cover the pan because the wheat berries will pop as they toast. If your skillet is uncovered, you can expect a couple to launch themselves across your stove top. You don’t, however, want to trap moisture inside the pan. You want the wheat berries to toast, not steam.

Toasting the wheat berries before they cook

Toasting the wheat berries before they cook

When the wheat berries are nicely toasted, turn off the skillet and allow them to cool. Place them into a rice cooker or pan on the stove top with 3/4 cup water and bring to a boil (if you use a rice cooker, as we did, use the cook function and allow it to run through its cycle). If cooking on the stove top, reduce heat to a light simmer, cover the pan, and allow the wheat berries to cook for approximately 30 minutes. Check for doneness — the wheat berries should be slightly chewy with a firm texture, but completely tender. If your batch is still crunchy, allow to simmer/steam a little longer…check every 5 minutes, adding more water if necessary and maintaining a light simmer.

When the wheat berries are tender, drain any remaining water from the pan and put them in a medium mixing bowl. (The toasting and cooking of the wheat berries can be done up to a day in advance — store in the refrigerator.) Allow them to cool and then stir in the olive oil, salt and parsley. Using your hands, mix in the ground beef and the minced garlic so that all ingredients are evenly incorporated.

Using a 1/3 cup measure (or ice cream scoop with a 1/3 cup capacity), measure out 1/3 cup of the meat mixture and form into a small patty approximately 1-inch to 1 1/2-inches thick. Continue to form patties with remaining meat mixture. You should be able to make approximately 9 slider patties with this amount of meat mixture. Place your sliders on a baking sheet and keep chilled in the refrigerator, covered with plastic wrap, until ready to cook.

To cook your sliders, heat a medium frying pan or skillet (a well-seasoned iron frying pan works very well for these) over medium high heat. Season your sliders on both sides with a little bit of Kosher salt and fresh ground pepper and, when the frying pan is quite hot, place them into the pan leaving approximately 1 to 2 inches between sliders. Do not crowd the pan or they will steam and will not develop the nice crust you are looking for.

If all the sliders will not fit in your pan (mine did not — only got 5 in the first batch), cook them in batches. Allow the sliders to sear, undisturbed, for 3 minutes before flipping. No poking or squishing! If your pan was hot enough the sliders will have developed a crust and will flip easily after the initial 3 minutes. If your sliders do not have a crust at this point or are sticking to the pan, turn up the heat a bit and cook for another 30 seconds to 1 minute to further sear — they may be a little more well done this way, but will release more easily from the pan. The maillard reaction that occurs during searing caramelizes the natural sugars in the meat and helps keep the sliders from sticking. You want this to happen early in the cooking process for the best results and easiest-to-flip sliders.

Once flipped, cook for another 3 minutes on the second side. This amount of cooking time gives you medium-rare sliders. If you like yours more well-done, cook for an additional minute to 2 minutes. Remove from the pan, sprinkle with some of the feta cheese if using, and allow to rest for 10 minutes. (The feta will begin to melt onto the patties as they rest.)

If cooking in batches, prepare the second batch in exactly the same manner. By the way…if you’re topping these with sautéed baby spinach, just wipe the skillet mostly clean and lightly sauté a couple of handfuls over medium heat after you’ve finished the burgers.

To make the mint mayo, place the mint, mayonnaise, garlic, vinegar and salt in a blender and process by slowly working up to the highest setting. Mayo is done when it is bright green and well blended.

Assemble sliders by spreading a small amount of mint mayo on both the inside bottom and top of your roll or bun. Stack one of your sliders, plus any of the condiments, between the bun and enjoy!

Serves: 6 – 8 (figure on 1 to 2 sliders per person…these are filling, but hungry adults could eat 2)

Kid rating: three-and-a-half stars. Daughter 1 is not a big meat eater so sliders don’t hold the hugest appeal but she finished hers happily. Daughter 2, on the other hand, really enjoyed these. Both girls got into making them, and ended up eating theirs “deconstructed:” burger, roll, and toppings. With our girls, just make sure to hold the mint mayo.
Parent rating: four stars from me — great beef taste that works well with the feta, mint, onions and spinach. I enjoyed the wheat berries in these sliders, too. They pop ever so slightly as they are being chewed and add a subtle textural element that I really liked. My husband was out of town the night we had these so I can’t honestly provide a rating from him…but lets just say he’s a bit of a burger purist. There was probably a reason I made them the night that I did. If you’ve gotten this far in this recipe though, chances are that you’re willing to forgo White Castle for the evening give these reinvented sliders a try. Let me know how many stars you and your family give this dish!

2 thoughts on “Beef and Wheat Berry Sliders with Feta, Caramelized Onions, Baby Spinach and Mint Mayo

  1. Pingback: Easy Oven Fries | The Stout Sprout

  2. Pingback: Brown Rice, Wheat Berry and Quinoa Salad with Cucumber, Sun-dried Tomatoes, and Roasted Red Peppers | The Stout Sprout

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