Spicy Juicy Lucy Mini Burgers

Ingredients:

• 2 tbsp. l. olive oil
• 1 large onion, thinly sliced ​​(about 3 cups)
• 2 chipotle peppers in adobo sauce, finely chopped
• 2 cloves garlic, crushed
• 700 g of ground beef
• 110 g pepper jack cheese, divided into 12 equal parts
• 1/4 cup ketchup
• 1 tbsp balsamic vinegar
• 12 mini potato buns, halved and toasted

Preparation:

1. Heat olive oil in a large skillet over medium heat and add the onion, spreading it out evenly. Cook, undisturbed, until the edges of the onion begin to brown, 5 minutes. Stir the onion and continue cooking, stirring occasionally, until golden brown and caramelized, another 20 minutes. Add the chipotle pepper, garlic, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Cook until fragrant, stir thoroughly, 1-2 minutes, and remove from heat.
2. Preheat the oven to broil. Divide the ground meat into 12 portions, each weighing 55-60 grams (1.9-2.3 oz). Insert a piece of cheese into each portion and form patties 6-8 cm (2.5-3.5 in) in diameter. Place the cheese-filled patties on a foil-lined baking sheet and sprinkle each patty with 3/4 teaspoon of salt.
3. Grill in the oven until the cheese is melted and the patties are still slightly pink on the inside, about 6 minutes. The patties should be cooked to at least medium-rare so the cheese is melted but still juicy.
4. In a small bowl, combine the ketchup, balsamic vinegar, and 1/4 teaspoon of black pepper. Brush the patties with the sauce. Spread the remaining sauce on the bottom bun halves. Place a patty on each bottom bun, top with some hot onions, and cover with the top bun halves. Serve the burgers warm.