How to Make It
In a large nonstick skillet, heat 2 tablespoons of the vegetable oil until shimmering. Add the tofu and stir-fry over high heat until starting to brown, about 1 minute. Add the pickled mustard greens and stir-fry until sizzling, about 30 seconds. Transfer the tofu and greens to a plate.
Add the remaining 2 tablespoons of vegetable oil to the skillet. Add the spinach by the handful and cook over moderate heat, stirring to wilt the leaves before adding more, about 4 minutes. Return the tofu and pickled mustard greens to the skillet and toss. Add the soy sauce and bean sprouts, drizzle with the sesame oil and remove from the heat. Lightly season the stir-fry with salt and pepper, toss well and serve immediately.
Pickled mustard greens are available in cans and packages at Asian markets.