Chicken Burgers with Barbecue Onion Sauce

From Every Day with Rachael Ray June/July 2007

2 lb ground chicken
2/3 C grated parmigiano-reggiano or pecorino romano cheese (a couple generous handfuls)
4 cloves garlic, finely grated
3 Tbsp finely chopped fresh rosemary leaves
1 1/2 Tbsp fennel seeds, toasted
1 tsp crushed red pepper
1/4 tsp ground allspice
Grated peel and juice of 1 orange
Salt and black pepper
2 Tbsp EVOO, plus more for drizzling
1/4 lb pancetta, chopped
2 red onions, chopped
1 bay leaf
1/2 balsamic vinegar
3 Tbsp honey or brown sugar
2 Tbsp Worcestershire sauce
4 crust rolls, split
1 C arugula leaves, shredded
1/2 head endive, chopped
1/2 head radicchio, chopped

Preheat grill or grill pan to medium-high. In a large bowl, combine the chicken, cheese, garlic, rosemary, fennel seeds, crushed red pepper, allspice, orange peel and 1/4 teaspoon salt; season with black pepper. Form the mixture into 4 patties, pressing your thumb into the center of each to keep it from bulging as it cooks. Set patties aside.
In a medium skillet set on the grill, heat 2 tablespoons EVOO, 2 turns of the pan. Add the pancetta and cook until crisp, 3-4 minutes, then add the onions and season with salt and lots of black pepper. Add the bay leaf and cook, stirring occasionally, until the onions begin to brown, about 10 minutes. Discard the bay leaf. Stir in the vinegar, honey, Worcestershire sauce and orange juice and cook, stirring occasionally, until thickened, 6-7 minutes (if the sauce begins to dry out, stir in a little water).
Drizzle the patties liberally with EVOO. Grill until form to the touch but still juicy, about 5 minutes on each side. Transfer to a plate to rest for 5 minutes. Toast the rolls on the grill and drizzle with EVOO. Set aside.
In a medium bowl, toss together the lettuces; pile onto the roll bottoms. Top each with a patty, onion sauce and a roll top.