Optional toppings: sliced red onion, lettuce leaves, salsa and sour cream
In a large bowl, combine the first nine ingredients. Add chicken; mix lightly but thoroughly. Shape into four 3/4-in. thick patties.
Moisten a paper towel with cooking oil; using long-handled tongs, rub on grill rack to coat lightly. Grill burgers, covered, over medium heat 7-8 minutes on each side or until a thermometer reads 165°. Serve on buns with guacamole and additional toppings as desired.