Preheat broiler or gas grill to medium/high heat.

Prepare the Tarragon Aoli by combing all ingredients. Refrigerate to let flavors combine.

Saute chopped onion in either a small amount of vegetable oil or cooking spray until transluscent. (I do this because my stomach can''''t "do" raw onions - you can skip this step and leave the onions raw.)

Combine the sauteed onion and the next 6 ingredients in a large bowl. Divide turkey mixture into 8 equal portions, shaping each into a 1/2-inch-thick patty. (If preparing in advance, either put patties between wax paper or some other separator and refrigerate. If possible - for faster cooking time, pull the patties out of the refrigerator 30 minutes prior to cooking to bring the meat to room temp.)

Slice Kaiser rolls in half (as like hamburger buns.) Butter each cut side and lightly sprinkle with garlic salt. (If preparing in advance, this step can be completed and then put the rolls together and put in the refrigerator.)

Place patties on a broiler pan coated with cooking spray; broil 6-8 minutes on each side or until thoroughly cooked or place patties on grill coated lightly with oil. Let burgers rest for 5 minutes after cooking.

Toast the Kaiser roll halfs under the broiler or on the grill (place the buttered side toward the heat source - which would be up for the broiler and down for the grill.)

Serve on toasted Kaiser rolls with Tarragon Aoili, sliced avocado, tomato and lettuce. The burger doesn't need much else - but you can each cheese if you want to!