This crispy black pepper tofu is smothered in spicy sauce stir-fried with sweet bell peppers and crispy celery. Serve over rice for a flavor-packed meal that's totally doable on a weeknight.
Stir the sauce ingredients together in a small bowl or container.
Place the cornstarch into a small bowl.
Generously coat the bottom of a wok (or large nonstick skillet) with peanut oil, adding enough oil for a depth of about ⅛ inch. Place the wok over medium heat.
Place the tofu cubes into the bowl of cornstarch, a few at a time. Lightly dredge the tofu cubes in cornstarch, then transfer them to the wok, placing them in a single layer (Note 2).
Cook the tofu for about 10 minutes, flipping the pieces about halfway through, until the pieces are lightly browned and crispy. Transfer the pieces to a plate when they're done.
If the wok still has a lot of oil in it at this point, carefully wipe most of it out, leaving a thin coating.
Raise the heat to medium-high. Give the wok a minute to heat up, then add the bell pepper and celery. Stir-fry the vegetables for about 2 minutes, until they begin to deepen in color.
Add the garlic, ginger, and white parts of the scallions to the wok. Continue stir-frying everything for about 30 seconds, until the aromatics become very fragrant.
Return the cooked tofu to the wok, then carefully pour the sauce over the tofu and vegetables. Mix up the ingredients and continue stir-frying the mixture for about 1 minute, until the sauce thickens slightly and coats the tofu and vegetables.
Remove the wok from heat. Add the green parts of the scallions.
Divide onto plates and serve with rice.