Tex-Mex Chicken Burgers

Prepare Chipotle Salsa: Preheat grill to medium-hot. Grill tomatoes, tomatillos, onion, and garlic 10 minutes, or until charred and softened. Let cool. Peel garlic. In a food processor, finely chop garlic; add tomatoes, tomatillos, onion, and pulse, just until finely chopped. Pour into a bowl; stir in cilantro, chipotle, salt, and sugar. Prepare Burgers: In a bowl, mix chicken, breadcrumbs, mayonnaise, egg, scallion, chile powder, cumin, salt, and pepper until well blended. With lightly moistened hands, shape into 4 burgers (about 3/4-inch thick). Oil grill and spray burgers with nonstick spray. Grill burgers 6 minutes per side, or until cooked through. Grill corn cakes until toasted on both sides. To assemble burgers, top each corn cake with a burger, a spoonful of salsa, and sliced avocado. Serve with remaining salsa on the side. Garnish with cilantro.