Peel the sweet potato and coarsely grate, using the largest holes on a hand-held grater. Add the grated potatoes to a bowl, and squeeze with a couple of paper towels until fairly dry. Add the scallions, jalapeño, flour, salt, Ancho chili pepper powder, and black pepper. Lightly toss using your hands to coat the grated sweet potato.

Add the egg and thoroughly mix, using a fork. Form 8 latke haystacks, each a little more than 2 tablespoons (⅛ cup), and place on a plate or wooden board next to the stove. Feel free to double the size for a side dish of latkes, or an entrée.

Heat the oil in a deep 12-inch nonstick skillet, such as the Analon Accolade, over medium-high heat until shimmering hot. Carefully arrange the latke haystacks around the skillet. They should sizzle a bit when they hit the oil, but not splatter. Gently flatten them using a fork to about 2 ½ inches in diameter.  Cook until golden, about 2 ½ - 3 minutes on each side. Look for the edges to start to crisp. Gently turn over using the fork. They shouldn't break apart at all. If they do, they need to get a little crisper. Immediately drop a little grated cheddar on top, and cook for another 3 minutes. You may need to cover them for the final 30 seconds to melt the cheese. 

Place a cooling rack over paper towels. Transfer latkes with a spatula or fork to to cooling rack to drain. Although this recipe uses very little oil, draining them directly on paper towels can make them a little greasy unless you immediately remove them. I prefer to use a cooling rack.

In a small bowl, mix together the sour cream and lime juice.

While still warm (but not hot), place a dollop of sour cream on each latke, and finish with a shower of chives. These are best eaten warm. For an appetizer, they shouldn't more than 2 bites, and 1 bite is even better. 

An alternate topping is applesauce.