Makes 4 regular burgers or 8 sliders 1 tablespoon olive oil

4 large sweet onions, sliced

1 tablespoon balsamic vinegar

1 pound lean ground beef

1/2 teaspoon salt

1/4 teaspoon ground black pepper

1/2 teaspoon cumin

1/4 teaspoon cayenne pepper

1 teaspoon smoked paprika

1/2 teaspoon garlic powder

1 tablespoon honey

1 tablespoon tomato paste

1 teaspoon Dijon mustard

3 tablespoons apple cider vinegar

1 tablespoon soy sauce

4 standard or 8 slider whole-grain burger buns

1. In a large skillet over medium, heat the olive oil. Add the onions and saute until deep brown, about 20 to 25 minutes. If the skillet gets too dry, add 1 to 2 teaspoons of water as needed. Stir in the balsamic vinegar and allow to cool.

2. Heat the grill to medium-high.

3. In a medium bowl, gently stir together the cooled onions, ground beef, salt and black pepper. Form the mixture into 4 or 8 patties, pressing a slight indent into the center of each.

4. In a small saucepan that can be heated on an outdoor grill and one with a heatproof handle, combine the cumin, cayenne and smoked paprika. In a small bowl, stir together the garlic powder, honey, tomato paste, mustard, cider vinegar and soy sauce. Bring everything out to the grill.

5. Place the saucepan with the spices directly on the grill. Stir until fragrant and toasted, about 1 minute. Add the tomato-honey mixture to the spices and stir until simmering, about 5 minutes. Use caution; the handle of the saucepan will get very hot. Move the saucepan to the back of the grill or off to the side.

6. Add the burgers to the grill and cook to the desired doneness. Spoon the sauce over the burgers and serve on multigrain or whole-wheat buns.

From Alison Ladman for The Associated Press