Place a large, deep skillet over medium heat. After about a minute, add 1 tablespoon of the oil and swirl to coat the pan. Add the mushrooms and stir-fry over medium-high heat for 5 minutes. Stir in the jalapeños, plus 1/8 teapoon of the salt, and cook, stirring frequently, for 5 to 8 minutes longer, or until the mushrooms are very limp. Push the mushrooms and jalapeños to one side of the pan, then add another tablespoon of oil to the exposed surface, followed by the cabbage and another 1/8 teaspoon of the salt. Keeping the heat medium-high, stir-fry the cabbage only for about 3 minutes, then mix in the sidelines mushrooms and jalapeños. Spread out the mixture, cover the pan, and let it steam (okay if it scorches slightly) for about 5 minutes. Scrape the bottom of the pan and mix intermittently. In a small bowl, combine the soy sauce, vinegar, and sesame oil, then pour this in. Mix well, cover, and continue to cook over low heat for another 5 to 8 minutes, or until done to your liking. Transfer to a serving bowl and set aside. Without cleaning it, return the pan to the stove over medium heat. Wait about a minute, then add a little oil and swirl to coat the pan. Turn up the heat to high and flash-cook the onions, shaking the pan, for only about 1 to 2 minutes, or until the onions become shiny and golden on the edges but are still crunchy. Add these to the cabbage mixture in the bowl. Return the uncleaned pan to the medium heat one more time, wait another minute, add another little but of oil, and swirl to coat the pan. Add the tofu in a single layer (okay if touching) and cook undisturbed for about 5 minutes on each side, or until crisp and deep golden brown. Toss into the cabbage mixture and serve. Pass around the sesame oil, so people can add a little extra, if they wish.