Steak Smash Burgers with Poblano Aioli Recipe

I love this recipe because it's sloppy and delicious. The smoky, roasted poblano aioli brings out the bold, beefy flavor of the burgers while brightening them up at the same time. Plus, the scratch-made brioche bun really sends it over the top!

Technique tips: Place the steak cubes into the freezer for 10 minutes to blast chill before grinding, so it's not gummy when grinding.

Freeze any leftover buns in large zip-top bags. Thaw the buns at room temperature, 30 minutes to several hours ahead, in the bag before serving.

If you’re using my homemade mayonnaise, only use 1 teaspoon lemon juice while following this recipe, otherwise it’ll be too lemony and thin. If using store-bought, you'll need 2 tablespoons.

To toast the brioche buns, split, spread with butter and place on the hot griddle or skillet until toasted.

Swap option: You can use 80% lean ground beef.

For the brioche buns:

In a medium bowl, stir the yeast, 2 tablespoons sugar and warm water. Let the mixture set until it becomes very foamy, 10 to 15 minutes.

In a small bowl, whisk 1 egg and the egg yolk together until combined.

In the bowl of a stand mixer, add the flour, salt and remaining 2 tablespoons sugar, and use the dough hook attachment to stir together by hand. Fit the dough hook onto the stand mixer.

With the mixer on low speed, pour in the egg and yeast mixture. Pushing the mixture down along the perimeter with a rubber spatula, coaxing the flour to pull together in a loose ball.

Once it begins to form, add the butter cubes, one at a time, while mixing. Continue kneading the dough over low speed, about 10 minutes. When all the dough accumulates on the dough hook, stop the mixer and push the dough down into the bowl and continue mixing. You'll need to do this several times. The dough is going to be very sticky (don't worry — that's normal!).

Lightly oil the inside of a large bowl and oil a piece of plastic wrap, large enough to cover the bowl.

Dust a rubber spatula and your hands with flour, to help you remove the dough from the mixing bowl and transfer it to the oiled bowl. Flip and coat the dough in the oil all over and cover the bowl with the plastic wrap, oiled side down.

Place the bowl in a cold oven and turn on the light. This gives the oven some heat to proof. Or, if you have the proofing function on your oven, turn it on to 100 F. Let the dough proof until doubled in size, 1 to 1½ hours.

Remove the bowl and punch down the dough.

Transfer the dough to a non-floured work surface; you'll need the countertop to slightly grip the dough to roll each piece into a ball. Dust a rubber spatula and your hands with flour. Divide the dough into 10 equal pieces. Shape each piece into a ball, tucking the edges underneath and place seam-side down onto the non-floured countertop, cup it with the palm of your hand and move it in a circular motion, forming a ball. Gently flatten into 2½- to 2¾-inch diameter slightly flattened balls. Arrange 1 inch apart among a parchment paper-lined rimmed baking sheet. Cover with a clean kitchen towel. Place the baking sheet into the cold oven and turn on the light or set the proofing function to 100 F. Let the dough proof again until doubled in size, 45 minutes to 1 hour.

Remove the dough before heating the oven.

Heat the oven to 375 F.

In a small bowl, crack the remaining egg and whisk until beaten. Gently (careful not to deflate the dough) brush the tops and sides of the buns with the remaining beaten egg. Sprinkle the tops with sesame seeds, if using.

Bake until lightly golden, 12 to 14 minutes. Remove the buns to cool. Slice in half, crosswise, when ready to serve.

For the smash burgers:

Grind the steak in a meat grinder or in a food processor fitted with the blade attachment until finely ground. If using a food processor, pulse-chop until finely ground; don't whip it or the meat will get gummy. Clean the food processor, if using. Leave the steak at room temperature while preparing everything else.

Adjust oven rack to the top position. Heat oven to broil.

Line a rimmed sheet pan with foil. Add the onion slices and poblano (don't cut it!). Drizzle a little oil over the onions and poblano. Season lightly with salt and pepper. Toss and broil until charred in spots, 6 to 7 minutes, turning poblano halfway, and toss onions periodically while broiling.

Remove the poblano to a small bowl and cover with plastic wrap to steam, releasing the skin. Once cool enough to handle, peel away and discard the skin, stem and deseed the poblano.

Add the grated garlic and lemon juice into a small bowl. Let set 1 minute. It mellows the garlic. Add the mayonnaise, cilantro, roughly torn poblano, 1/2 teaspoon salt and 1/4 teaspoon pepper into a food processor fitted with the blade attachment. Puree until chunky smooth. Stir in the lemon zest. Remove to a bowl and cover. Refrigerate to set until ready to use. You can make this up to 2 days ahead; keep refrigerated.

Heat a griddle or 12-inch cast-iron skillet over medium to medium-high heat for 5 to 10 minutes. Cut a 5-inch parchment paper square.

Season the ground steak generously with salt and pepper. Divide and form into 4 burger balls, 5 ounces each.

Lightly drizzle the steak balls with oil to evenly coat. Lightly drizzle oil over griddle or cast-iron skillet. When the oil is heated and shimmers, add the steak ball. Immediately place the parchment square directly on top. With a spatula, quickly press to smash into a 1/2-inch-thick burger. Hold 10 seconds to lock in the moisture and get a good sear.

Cook 2 to 2½ minutes on each side for medium doneness. In the last 30 seconds, add a slice of cheese on top of the burger, cover with a lid, if needed, to help it melt. Remove to a plate to rest; keep warm. Repeat with remaining burgers.

Spread poblano aioli on bottom burger bun, top with romaine leaf, cheeseburger, tomato slice, salt and pepper and fried onions, and smear more poblano aioli over the top bun to close.