These juicy burgers are irresistibly buttery and delicious!
unsalted butter, at room temperature
freshly ground pepper
ground beef sirloin
soft hamburger buns, split
Preheat the broiler. Melt 2 tablespoons butter in a large cast-iron skillet over medium heat.
Add onions and cook until translucent, 6 to 8 minutes.
Add 1/3 cup water, cover and continue cooking until the onions are golden brown, about 15 more minutes. Season with salt and pepper. Transfer the onions to a bowl and wipe out the skillet.
Divide meat into 6 loose balls, then gently flatten into thin patties. Heat the skillet over high heat. Add the patties to the hot skillet, smash them flat with a spatula and season with salt and pepper. Cook, flipping once, until well done, about 3 minutes per side.
Meanwhile, toast the buns under the broiler. Put the patties on the bottom buns and top each with 1/4 cup sauteed onions. Smear 2 tbsp butter on the cut side of each top bun, then put on top of the burgers. Slice in half and serve immediately.