In a small bowl, mash fermented tofu with a fork. Add the furu sauce, wine, soy sauce and salt and mix until smooth.
Set a large pot of water to boil. Wash yu choy and separate any particularly large, multi-stemmed stalks into single stalks. Cut long stalks into large bite-size pieces. You can leave short stalks whole. (If using very small baby bok choy, cut in half vertically; cut larger bok choy into large bite-size pieces.) Add greens to boiling water for just 30 seconds. Remove with tongs and shake excess water off the greens. Rest them on a paper-towel lined plate or bowl to absorb additional water.
Working quickly, heat wok over a medium flame and add 1 tablespoon neutral oil. Add sliced garlic and cook until it is lightly golden, stirring constantly so it doesn't burn. Add furu sauce and bring to a simmer. Add yu choy and gently stir-fry it in the sauce. Cook just until the yu choy is done to your liking, 1-2 minutes, depending on stalk size. Remove yu choy to a plate and pour sauce over the top of it. Serve hot.
