4 large (8 cups) sweet onions, thinly sliced (Vidalia onions are great for this recipe.)
4 large (6 cups) red bell peppers, thinly sliced
1/2 cup cider vinegar
1/4 cup packed brown sugar
2 tbsp honey
2 tbsp canola oil
2 tsp celery seed
3/4 tsp crushed red pepper flakes
1/2 tsp salt
In a 5 or 6-qt slow cooker, combine all ingredients. Place lid on cooker and cook on low 4 to 5 hours or until veggies are tender.
Serve with a slotted spoon.
Serving suggestions - on hot dogs, bruschetta, etc.
Source: I got this recipe last year from TOH.