Grilled Beef Burger with Caramelized Onions

Method

1. Heat olive oil in a skillet over medium heat.
2. Add sliced onions and cook until softened, about 5 minutes.
3. Stir in brown sugar and balsamic vinegar, then cook until onions are caramelized, about 10 minutes.
4. Form ground beef into 4 patties.
5. Grill patties over medium-high heat until cooked to desired doneness, 4-5 minutes per side.
6. Toast sesame seed buns and assemble with lettuce, patty, caramelized onions, and ketchup.
7. Check that the ground meat reaches 71°C (160°F) throughout before serving.