Preheat oven to 400°F

Toss sweet potato, onion, bell peppers, olive oil, lime juice, cumin, chili powder, cayenne pepper and salt in bowl.

Transfer mixture to rimmed baking sheet. Bake for 25 minutes or until sweet potatoes are tender, stirring halfway through.

Warm black beans.

Fill flour tortilla with potato mixture and black beans. Top with avocado slices and feta cheese.