Press the tofu for 15 minutes under a weighted plate, then tear it into rough 2 to 3 cm chunks. Torn edges crisp better than knife-cut cubes.
Toss the tofu with 3 tbsp cornstarch and a big pinch of salt until every piece is coated and dry looking.
Stir the soy sauce, black vinegar, sugar, water, and 2 tsp cornstarch together. That is the whole sauce.
Heat the oil in a wide nonstick pan over medium-high. Add the tofu in one layer and leave it alone for 3 minutes before turning. Fry until golden on most sides, about 8 minutes total, then move to a plate.
In the same pan, toast the dried chilies and Sichuan peppercorns for 30 seconds until fragrant but not blackened. Add the garlic and ginger and stir for another 30 seconds.
Add the edamame and stir-fry for 1 minute, then pour in the sauce. It will thicken in about 30 seconds.
Return the tofu, add the peanuts and scallions, and toss just until everything is glossy. Serve immediately, with rice if you have the calories to spare.