Braised Tofu with Preserved Mustard Greens and Peanuts

Prepare the ingredients. Drain and pat dry the firm tofu, then cut into 2cm cubes. If using dried preserved mustard greens, rehydrate them by soaking in water for at least 30 minutes. Squeeze out excess water, then finely chop. Chop garlic and ginger. Cut scallions into 2-inch lengths, separating white and green parts.