Mix yogurt, mint, cilantro, and lime peel in small bowl. Season to taste with coarse salt and pepper. Cover; chill until cold, at least 30 minutes.
For burgers and vegetables:
Heat 2 tablespoons oil in large skillet over medium heat. Add onion, ginger, and 1/2 teaspoon coarse salt. Sauté until onion is tender, about 8 minutes. Mix in curry powder and stir 30 seconds. Remove from heat. Cool onion mixture to room temperature, at least 15 minutes.
Place lamb in large bowl. Add onion mixture, 1 teaspoon coarse salt, cilantro, and 1 teaspoon cracked pepper. Blend mixture gently; shape into six 1/2-inch-thick patties.
Prepare barbecue (medium-high heat): Combine zucchini, green onions, and chile in another large bowl. Add 2 tablespoons oil, 1/2 teaspoon coarse salt, and 1/2 teaspoon cracked pepper; toss to coat. Place vegetables and burgers on grill. Cook until grill marks appear, about 4 minutes. Turn vegetables and burgers over. Cook vegetables until tender, about 3 minutes. Cook burgers to desired doneness, about 4 minutes for medium-rare. Cut zucchini and green onions crosswise into 2-inch-long pieces. Cut chile into thin strips.
Place bread on plates, top with burgers and tomatoes. Pile grilled vegetables on burgers and spoon raita over top. Fold bread up around burgers and serve with raita.