Instructions: Blend first 3 ingredients in bowl; season mayonnaise with salt and pepper.

Using meat mallet, flatten chicken breast halves in plastic bag to 1/2-inch thickness; cut chicken crosswise in half. Place on sheet of foil. Brush chicken with 1 tablespoon oil; sprinkle with half of garlic, then salt and pepper.

Place zucchini and onion slices on sheet of foil and brush with remaining 2 tablespoons oil; sprinkle with remaining garlic, then salt and pepper.

Prepare barbecue (medium-high heat). Grill chicken pieces until cooked through, about 5 minutes per side; transfer to work surface. Grill vegetables until softened slightly and charred, about 7 minutes per side for onion and 5 minutes per side for zucchini. Transfer to work surface.

Grill rolls until toasted, about 2 minutes per side. Spread tarragon mayonnaise on roll bottoms; top with 1 chicken piece, 1/4 of grilled vegetables, and 2 tomato slices. Cover with roll tops.

This recipe yields 4 servings.

Comments: Carey Paquette of Arlington, Virginia, writes: "My boyfriend and I cook almost every night as a way to unwind. Its nice to come home after a hectic day and make dinner together rather than pull something prepackaged out of the freezer. One of our favorite things is grilled vegetables. Im always adding them to meals, since they dont need a lot of preparation. Theyre the key ingredients in my popular chicken sandwiches."

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