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 and up to 4 hours.
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 breads on plates; top with burgers and tomato slices. Mound vegetables on burgers; spoon dollop of raita over. Fold bread up around burgers and serve with remaining raita.
* Often called a pasilla; available at some supermarkets and at specialty foods stores and Latin markets.