Preheat grill to high heat (450-550°F).

Cut zucchini and red bell peppers into 1-inch chunks.

In a large bowl, combine yogurt, cilantro, garam masala, salt, curry powder, cayenne, lemon juice, and olive oil.

Add lamb and vegetables to the bowl and toss to coat evenly.

Thread lamb and vegetables onto metal skewers, leaving space between pieces.

Grill skewers for about 5 minutes, until they begin to char and are easy to turn.

Turn skewers as needed and continue grilling until lamb is medium-rare and vegetables are tender-crisp, about 8-10 minutes total.

Transfer skewers to a platter.

Garnish with cilantro sprigs before serving.