A quick, healthy and light weeknight dinner that serves 2 on its own or 4 with some short-grain brown rice, quinoa or other grain alongside it.
Dry tofu well between several layers of paper towels. Cut into approximate 1/2-inch cubes and dry again. Place in a mixing bowl and sprinkle with cornstarch, salt and pepper. Toss gently to coat evenly.
Warm 2 tablespoons of the oil over medium-high heat in a 12-inch nonstick skillet. Add tofu in a single layer and cook until golden brown on the bottom, then stir once in a while and continue cooking until most sides are golden. This will take about 10 minutes total. Slide tofu out onto a plate.
In the same pan, heat the remaining tablespoon oil. Add bell pepper and mushrooms and cook for a few minutes, stirring only occasionally, until mushrooms have browned in spots and peppers are slightly tender. Add cabbage, tamari and vinegar and cook, stirring, until cabbage is tender and reduced in volume by at least half, which will take only a couple of minutes.
There will be some tasty liquid at the bottom of the pan. Depending on your sauce preferences, you can remove the vegetables from the skillet with tongs or a strainer to avoid the liquid, go with the flow and serve it as-is, or remove the vegetables and then simmer the liquid down into a thicker sauce. (The cornstarch from the tofu will aid this process.)
Place vegetables on serving plates (alongside rice or other grains if you like) and top with reserved tofu. Sprinkle with chili sesame oil and cilantro as well as sauce if you like. Serve immediately.