Prepare the Sweet Potatoes: In a medium pot of salted boiling water, add the diced sweet potatoes and cook until tender, about 10-12 minutes. Drain and set aside.
Cook the Turkey: While the sweet potatoes are cooking, heat the olive oil in a large skillet over medium-high heat. Add the chopped onion and sauté for 3-4 minutes until soft. Stir in the minced garlic and cook for 1 more minute until fragrant.
Season and Brown the Turkey: Add the ground turkey to the skillet. Season with cumin, smoked paprika, chili powder, salt, and pepper. Cook, breaking up the turkey with a wooden spoon, until browned and fully cooked, about 6-8 minutes.
Combine Ingredients: Once the turkey is cooked, gently fold in the cooked sweet potatoes and black beans (if using) into the skillet. Stir until everything is well mixed and heated through. Taste and adjust seasoning if necessary.
Warm Tortillas: In a separate skillet or directly over a flame, warm the corn tortillas for about 30 seconds on each side, until pliable.
Assemble the Tacos: On each tortilla, add a generous scoop of the turkey and sweet potato mixture. Top with avocado slices, fresh cilantro, and a squeeze of lime.
Serve: Serve the tacos warm with additional lime wedges and your choice of salsa or hot sauce on the side.