How to Make It
In a large baking dish, whisk the vinegar with the minced scallions, soy sauce, oyster sauce, ginger, garlic and chiles. Add the ribs and stir to coat. Cover the baking dish and refrigerate overnight.
Set a rack over a large baking sheet. Spread the cornstarch in a large baking dish. Remove the ribs from the marinade and let any excess drip back into the dish. Dust the ribs in the cornstarch and transfer to the rack.
In a large saucepan, heat 2 inches of canola oil to 325°. Line another baking sheet with paper towels. Add one-third of the ribs to the hot oil and fry over moderately high heat, turning occasionally, until browned and crisp, about 8 minutes. Transfer to the paper towel-lined rack and season lightly with salt. Repeat with the remaining ribs.
In a bowl, whisk all of the ingredients until combined.
Transfer the ribs to a platter, garnish with thinly sliced scallions and serve with the dipping sauce.