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Savory Cast Iron Grill Smash Burgers with Caramelized Onion Sauce

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These smash burgers feature a crispy crust from a cast iron skillet and a rich, luscious caramelized onion sauce, delivering juicy, flavorful bites perfect for quick and satisfying meals.

Ingredients

Scale
  • 1 lb ground chuck beef (80/20 blend)
  • Salt and freshly ground black pepper to taste
  • 1/2 teaspoon smoked paprika (optional)
  • 4 soft burger buns (brioche or potato buns recommended)
  • 1 tablespoon vegetable oil (for skillet prep)
  • 2 large yellow onions, thinly sliced
  • 2 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 1 teaspoon brown sugar
  • 2 tablespoons balsamic vinegar
  • 1/4 cup beef broth or water
  • Salt and black pepper to taste
  • Optional toppings: sharp cheddar or American cheese slices, pickles, lettuce, tomato slices, mustard or mayo

Instructions

  1. Prepare the caramelized onion sauce: Heat 1 tablespoon olive oil and 2 tablespoons butter in a medium skillet over medium-low heat.
  2. Add thinly sliced onions and sprinkle with 1 teaspoon brown sugar.
  3. Cook slowly, stirring occasionally, until onions soften and turn golden brown (20-25 minutes). Add splash of water or beef broth if onions stick or dry out.
  4. Stir in 2 tablespoons balsamic vinegar and 1/4 cup beef broth to deglaze the pan.
  5. Simmer for 5 minutes until sauce thickens slightly. Season with salt and pepper. Remove from heat and set aside.
  6. Form and season burger patties: Divide ground beef into 4 equal portions (about 4 oz each). Shape each into a loose ball without compacting.
  7. Season each ball generously with salt, black pepper, and smoked paprika.
  8. Cook the smash burgers: Preheat cast iron skillet over medium-high heat for 5 minutes until very hot.
  9. Add 1 tablespoon vegetable oil and swirl to coat.
  10. Place one or two beef balls on skillet without overcrowding. Press down firmly with spatula or burger press to flatten to about 1/4 inch thick.
  11. Cook without moving for 2-3 minutes until deep brown crust forms.
  12. Flip patty, add cheese slice if using, and cook 1-2 minutes until cheese melts and burger is cooked through.
  13. Repeat with remaining patties.
  14. Toast the buns: Slice buns and toast face down in a clean skillet or under broiler for about 1 minute until golden and slightly crispy.
  15. Assemble the burgers: Spread caramelized onion sauce on bottom bun.
  16. Place hot smash burger patty on top, add optional toppings like pickles or lettuce.
  17. Top with other half of bun and serve immediately.

Notes

Press patties firmly but avoid making them too thin to prevent drying out. Do not press down after flipping to keep juices sealed. Use a hot skillet and avoid overcrowding to get a perfect crust. Let burgers rest a minute after cooking. Caramelized onion sauce can be made ahead and tastes better after resting overnight. For gluten-free, use gluten-free buns or skip buns. For dairy-free, substitute butter with coconut oil or plant-based spread.

Nutrition

Keywords: smash burgers, cast iron skillet, caramelized onion sauce, quick burgers, easy dinner, juicy burgers, burger recipe

Find it online: https://magnetmeal.com/savory-cast-iron-grill-smash-burgers-with-caramelized-onion-sauce-recipe/