Spray a medium nonstick skillet with cooking spray; place over medium heat; add Onion and Garlic and sauté 3-5 minutes; add Bell Pepper and sauté 3-5 minutes more.
Transfer vegetable mixture to a large bowl; add Chicken, Yogurt, Breadcrumbs, Thyme and Cheese and season with Salt and Pepper to taste; cover and chill for 30 minutes.
Place all Relish ingredients in a small saucepan over low heat, stirring occasionally until all the sugar has dissolved; cover and cook two minutes, then remove lid and cook one minute more or until relish has thickened. Relish makes about 10 servings.
Spray barbeque grill with nonstick spray and preheat to medium high.
Form meat mixture into six patties; place patties on grill and cook 8-10 minutes per side or until browned and cooked thorough.
Serve burgers on buns with Corn & Carrot Relish on top and leafy lettuce under burger.