Pesto:
1 cup (packed) fresh mint leaves
1/2 cup (packed) fresh cilantro leaves
2 tablespoons pine nuts
2 tablespoons freshly grated Parmesan cheese
1 tablespoon fresh lemon juice
1 medium garlic clove, peeled
1/2 teaspoon coarse kosher salt
1/2 cup (or more) extra-virgin olive oil

Kebabs:
1 tablespoon extra-virgin olive oil plus additional for brushing
4 large garlic cloves, minced
2 teaspoons coarse kosher salt
1 1/2 teaspoons coriander seeds, ground in spice mill or in mortar with pestle
2 pounds trimmed boneless leg of lamb, cut into 1 1/4-inch cubes
2 large red bell peppers, cut into 1-inch squares
1 large red onion, cut into 1-inch squares

Special Equipment
6 to 8 metal skewers

For pesto:
Blend first 7 ingredients in processor to coarse puree. With machine running, gradually pour in 1/2 cup oil; puree until almost smooth. Transfer pesto to bowl. Season with salt and pepper.

For kebabs:
Mix 1 tablespoon oil, garlic, coarse salt, and coriander in medium bowl. Add lamb; toss to coat. Cover and chill at least 2 hours and up to 4 hours.

Prepare barbecue (medium-high heat). Thread lamb on skewers alternately with peppers and onions. Place on baking sheet. Brush with oil; sprinkle with pepper. Grill to desired doneness, turning occasionally, 7 to 9 minutes for medium-rare.

Arrange kebabs on serving platter. Drizzle each kebab very lightly with pesto and serve remaining pesto alongside.