Preheat the oven to 400F and line a sheet pan with parchment paper.
Cut the sweet potatoes into 1/4 inch wedges (or into fries if you so choose). The sweet potatoes do not need to be peeled.
In a large bowl, toss the wedges with olive oil, chili powder, cumin, salt and pepper. Transfer the sweet potato wedges to the sheet pan.
Bake until the wedges are brown and crisp on the bottom. You can leave them in longer if you prefer crispier wedges. Bake for 15 minutes, then flip over the wedges. Bake for another 15 minutes.
In a food processor, mix the garlic, avocado, yogurt, lemon juice, salt and pepper. Mix until the texture is smooth and creamy.
Enjoy the wedges with the sauce (or without)!