1/4 cup nonfat buttermilk
3 tablespoons canola mayonnaise
2 tablespoons minced fresh flat-leaf parsley
1 tablespoon minced shallots
1 teaspoon minced fresh thyme
1 teaspoon cider vinegar
1/4 teaspoon freshly ground black pepper
1/8 teaspoon kosher salt
1 garlic clove, minced
4 (6-ounce) skinless, boneless chicken breast halves
Cooking spray
1 1/2 tablespoons olive oil
1 teaspoon onion powder
3/4 teaspoon ground cumin
3/4 teaspoon kosher salt, divided
1/4 teaspoon chipotle chile powder
2 ears yellow corn, shucked
1 small red onion, cut into 1/2-inch slices
2 yellow tomatoes, each cut into 4 slices
2 red tomatoes, each cut into 4 slices
1 cup cherry tomatoes, halved
1 sliced peeled ripe avocado

1/4 cup nonfat buttermilk 3 tablespoons canola mayonnaise 2 tablespoons minced fresh flat-leaf parsley 1 tablespoon minced shallots 1 teaspoon minced fresh thyme 1 teaspoon cider vinegar 1/4 teaspoon freshly ground black pepper 1/8 teaspoon kosher salt 1 garlic clove, minced 4 (6-ounce) skinless, boneless chicken breast halves 1 1/2 tablespoons olive oil 1 teaspoon onion powder 3/4 teaspoon ground cumin 3/4 teaspoon kosher salt, divided 1/4 teaspoon chipotle chile powder 2 ears yellow corn, shucked 1 small red onion, cut into 1/2-inch slices 2 yellow tomatoes, each cut into 4 slices 2 red tomatoes, each cut into 4 slices 1 cup cherry tomatoes, halved 1 sliced peeled ripe avocado

1. Preheat grill to high heat.
2. Combine first 9 ingredients in a small bowl; stir with a whisk. Chill buttermilk mixture until ready to serve.
3. Lightly coat chicken with cooking spray. Combine oil, onion powder, cumin, 1/2 teaspoon salt, and chipotle; rub evenly over chicken. Coat corn and onion with cooking spray. Arrange chicken, corn, and onion on grill rack; grill 8 minutes or until done, turning chicken and onion once and corn occasionally. Remove from grill; let stand 5 minutes. Cut corn kernels from cobs.
4. Slice chicken. Arrange 1 breast on each of 4 plates. Arrange 2 yellow and 2 red tomato slices on each plate. Top each serving with 1/4 cup cherry tomatoes. Divide corn, onion, and avocado evenly among plates. Sprinkle 1/4 teaspoon salt over salads. Drizzle about 1 1/2 tablespoons dressing over each salad.