1. Slice tofu into strips or cubes and pat dry; roughly chop a bunch of the greens. Pan-fry the tofu in some vegetable oil until it browns on all sides, about 4 minutes; remove tofu from pan and pour off all but a little of the oil. Add the greens and pinch or two of red chili flakes, and continue cooking until the vegetables turn dark green, about 3 minutes.
2. Mix together a half cup of peanut butter, a couple of tablespoons of soy sauce, and fresh lime juice to taste; add a bit of water if necessary to get a nice consistency.
3. Add the sauce to the pan along with the reserved tofu and toss to coat. (You may not need to use all of the sauce, depending on how much greens/tofu you have). Garnish with crushed peanuts and serve.