Place onion, mushrooms, bell pepper, basil, garlic, salt and pepper in container of food processor fitted with metal blade. Cover and pulse until finely chopped.
Add onion mixture to ground turkey in medium bowl. Mix with hands until well combined. Form into four burger patties. (Patties will be moist).
Place on foil coated with cooking spray and set on prepared grill and cook about 5-6 minutes per side or until no longer pink and juices run clear.
If desired, place pineapple slices on grill and cook about 4-5 minutes per side.
For the Tzatziki Sauce: Combine all ingredients in container of food processor fitted with metal blade. Cover and process until well blended. Chill in refrigerator until ready to serve.
When ready to serve, top turkey burgers with grilled pineapple and Tzatziki sauce.
Kindly Submitted by “Inside Karen’s Kitchen”