From The TeamingUp Kitchen:
Sliders With Caramelized Onions

 Directions

1. Preheat broiler or grill. Heat the oil in a large nonstick skillet over medium heat. Add the onion and 1/4 tsp salt. Cook, stirring constantly, for 15 minutes or until golden brown.
2. In a medium bowl, add the beef, ketchup, steak sauce, garlic, 1/4 tsp salt, and pepper and combine with your hands until just mixed. Form into 6 burgers.
3. Grill burgers for 1 minute per side or until medium well. Tip: These burgers are smaller than your average 1/4 lb burgers, so keep a close eye on how fast they cook. It’s easy to overcook them and dry them out, so stay close to the grill.
4. Remove from heat and let the burgers sit for 3 to 5 minutes before placing in buns. Top each beef patty with about 2 tbsp caramelized onion and 1 to 2 arugula leaves (if you like). Serve with additional organic ketchup or other condiment of choice. Also feel free to top with cheese (will change nutritional information).