Sweet Potato Fajitas

Name: Sweet Potato Fajitas
Ingredients: 2 tablespoons olive oil; 1 clove garlic, minced; 1 teaspoon kosher salt; 1/2 teaspoon ground cumin; 1/2 teaspoon smoked paprika; 2 pinches ground cayenne pepper; 1 large sweet potato (about 1 pound); 8 to 10 small flour or corn tortillas; 2 medium bell peppers; 1 medium sweet or yellow onion; 1 cup plain Greek yogurt; Finely grated zest of 1 medium lime; Juice of 1 medium lime, divided; Kosher salt; Salsa, guacamole, lime wedges (optional)