Chicken-Eggplant Burgers

Onion Relish
1/4 Cup Olive Oil
3 Spanish (red) onion, thinly sliced
1 teaspoon sugar
2 tablespoons Balsamic Vinegar

Burgers
1/3 cup Extra-virgin olive oil
1 Eggplant, very thinly sliced, crosswise
4 boneless skinless chicken breast halves
Salt
Cayenne
Lettuce leaves
4 sandwich rolls, split

Step-By-Step

1. For the relish, heat the oil in a heavy-based pan over medium-low heat. Add the onions and cook, stirring occasionally, until soft, 7-10 minutes. Add the sugar and vinegar and simmer for 10 minutes. The relish will keep for 3 days, covered, in the refrigerator. Return to room temperature or reheat before use.
2. Prepare a fire in the charcoal or gas grill
3. Heat 4 tablespoons of the olive oil in a large, heavy-based frying pan over medium-high heat. Add the eggplant slices and cook until golden, 5-7 minutes. Drain on paper towels.
4. Lightly brush the chicken with olive oil and season with salt and cayenne. Grill until cooked through, with no pink remaining in the center, about 10 minutes, turning once. Lightly toast the cut sides of the sandwich rolls on the grill, then brush lightly with the remaining oil.
5.  To serve, place a lettuce leaf on the bottom half of each roll. Top with chicken, eggplant and relish. Cover with the top half and serve immediately.