In a large bowl, combine the grated sweet potato, flour, cornstarch, baking powder, salt, and black pepper. Mix well to combine.
Add the cold water gradually, stirring until the batter is smooth. The batter should be thick but pourable.
Fold in the shrimp, green onions, and cilantro until evenly distributed in the batter.
Heat about 1/2 inch of vegetable oil in a large skillet over medium-high heat.
Once the oil is hot, drop spoonfuls of the batter into the skillet, flattening them slightly with the back of the spoon. Fry in batches, making sure not to overcrowd the pan.
Cook for about 3-4 minutes on each side, or until golden brown and crispy.
Remove the fritters from the skillet and drain on paper towels.
Serve warm with your favorite dipping sauce.