Sweet Potato and Shiitake Mushroom Dumplings

In a food processor fitted with a dough blade combine flour and hot water; process until a tight dough forms. Transfer dough to a bowl. Cover with a damp clean cloth; let stand 20 minutes. 2. Meanwhile, in a large nonstick skillet cook sweet potato, mushrooms, ginger, and garlic over medium 10 minutes or until sweet potatoes are tender, stirring occasionally and adding water, 1 tablespoon at a time, as needed to prevent sticking. (Add as little water as possible.) 3. Add scallions and vinegar. Season with salt and pepper. Stir to combine. Taste and adjust seasoning. 4. Prepare assembly station: Fill a small bowl with water. Place cornstarch in a shallow dish. 5. Divide dough into teaspoon-size portions. Roll a portion between your palms to form a ball. Roll ball in cornstarch, then place on a cutting board. Using a rolling pin, flatten ball into a 3-inch disk. 6. Place a heaping tablespoon of sweet potato mixture in center of dough disk. Dip a finger in the water then run it along the edge of half of the dough disk. Bring the opposite edge over filling and press to seal edges completely. Pinch edges in a few places to create a pattern. Repeat with remaining dough and filling. 7. Bring a pot of water to boiling. Gently drop four dumplings into water. Boil 1 to 2 minutes or until dumplings float to top. Scoop out with a slotted spoon and set aside. Repeat with remaining dumplings. 8. For dipping sauce, in a small bowl whisk together soy sauce, sesame seeds, and 2 tablespoons water. Serve dumplings warm with dipping sauce.