Pepper Burgers With Caramelized Onions

Directions

1. 1
   Onions:.
2. 2
   Cut onions in half; cut each half into 1/2 inch thick slices.
3. 3
   Combine all ingredients in a 3 1/2 quart slow cooker.
4. 4
   Cook, covered, at HIGH 8 hours or until golden brown and very soft.
5. 5
   Store onions in an airtight container; refrigerate up to 2 weeks or freeze up to 2 months.
6. 6
   Yield: 2 cups.
7. 7
   Burgers:.
8. 8
   Shape beef into 4 patties.
9. 9
   Combine salt and next 4 ingredients; sprinkle evenly over both sides of patties.
10. 10
    Grill, covered with grill lid, over medium-high heat 5 minutes on each side or until beef is no longer pink.
11. 11
    Cook caramelized onions and vinegar in a saucepan over medium heat 5 minutes or until thoroughly heated.
12. 12
    Spoon over burgers.
13. 13
    Top with lettuce, and serve on rolls.