Whisk together soy milk, vinegar, hot sauce, garlic powder, and onion powder. Let sit 5 minutes.
Add plant-based chicken, tofu, or seitan to the soak, submerging fully. Cover and refrigerate at least 2 hours, or overnight.
Whisk together flour, cornstarch, and all seasonings in a shallow dish.
Remove a piece from the soak, letting excess drip off, and press into the seasoned flour, coating fully.
Dip back into the soak briefly, then back into the seasoned flour a second time, pressing firmly. Repeat with all pieces.
Let coated pieces rest 10 minutes before frying.
Heat oil to 350°F. Fry in batches, 4 to 6 minutes per side, until deeply golden and crisp.
Drain on a wire rack set over a baking sheet. Let rest a few minutes before serving.