Prepare the filling: Preheat the oven to 425°F. Line a baking tray with foil. Peirce 1 sweet potato, and bake for 40-50 minutes until tender. Peel, and set aside.
Meanwhile, heat olive oil in a pan over medium low heat. Add the onion, and cook on until golden, stirring occasionally, for about 20-25 minutes.
Reduce the heat to low, add the garlic, cooking for an additional 15-20 minutes. Add to the sweet potato and mash, season with salt and pepper to taste.
Make the dough: combine flour, cornstarch, turmeric, salt, ½ cup water and olive oil in a bowl or food processor until a dough forms. Add additional water, 1 tbsp at a time as needed. Cover in plastic wrap, and refrigerate for 15 minutes.
Combine cornstarch and water in a small bowl.
On a lightly floured surface, roll the dough to 1/8th inch thickness. Using a small knife, cut 3”x3”inch squares.
With your finger, run the cornstarch mixture around the edges of each square.
Place 1 tsp filling in the middle of the square. Flld into a triangle, and join the ends.
Set aside and repeat with all the dough and filling.
Cook in boiling water for 3-4 minutes, or until they float to the surface.
Serve in a bowl of soup, or fried with onions!