1. Preheat grill to medium-high heat.
2. To prepare relish, coat bell pepper pieces with cooking spray. Place pepper pieces on grill rack; grill 3 minutes on each side or until lightly charred. Remove from grill; cool slightly. Coarsely chop bell pepper pieces. Combine chopped bell peppers, parsley, and next 6 ingredients; set aside.
3. To prepare fish, brush 1 tablespoon oil evenly over fish. Sprinkle fish evenly with thyme, 3/4 teaspoon salt, and 1/2 teaspoon black pepper. Place fish on grill rack; grill 4 minutes on each side or until desired degree of doneness. Serve with relish.