Lamb and Sweet Potato Kebabs

In a large resealable plastic bag, combine ¼ cup olive oil, lemon juice, garlic, cumin, salt, and pepper. Add lamb; seal bag, turning to combine. Refrigerate for at least 8 hours or up to 24 hours.

Preheat grill to medium-high heat (350° to 400°).

Place sweet potatoes in a large saucepan, and add water to cover. Bring to a boil over medium-high heat. Reduce heat, and simmer until potatoes are just tender, 8 to 10 minutes. Drain well, and let cool for 20 minutes. In a medium bowl, toss together sweet potato, bell pepper, red onion, ¼ cup olive oil, salt, and pepper. Remove lamb from bag, discarding marinade. Thread lamb and vegetables onto skewers.

Spray grill rack with nonflammable cooking spray. Place skewers on grill, and cook, turning occasionally, until lamb reaches desired degree of doneness, about 3 to 4 minutes per side for medium.

In a small bowl, combine all ingredients. Season well with salt and pepper.