Pour the oil into a large, deep skillet. Heat until shimmering. Add the onions and celery and reduce the heat. When the onions start to release their liquid, add a pinch of salt. Saute until just translucent.
Stir in the garlic, ginger, and tofu and saute until fragrant. Stir in the cabbage and toss to coat.
Pour the stock over the tofu and veggies. Stir in the sambal oelek, soy sauce, tomato paste, and honey. Increase the heat and bring the mixture to a boil. Reduce to a simmer, and let cook uncovered for 15 minutes.
While the sauce is simmering, whisk the cornstarch into the water to form a slurry. Once the 15 minutes have passed, pour the slurry into the sauce and stir until the sauce thickens. Remove from the heat and stir in the peanut butter. Stir in the red chilies and cover to keep warm.
Place a large pot of water over high heat. Place a steaming basket on top and add the yu choy to the basket. Once the water is boiling, lift the basket and place the noodles in the pot. Cook the noodles according to the package's directions. My noodles took 4 minutes to cook and by that time my yu choy was a brighter shade of green and tender. If your noodles require more time to cook, remember to pull the yu choy before your noodles are done.
Drain and rinse the noodles and divide them among four plates. Add a few pieces of yu choy to the plate and a generous spoonful of the sauce. Top the dish with dry roasted peanuts and fresh mint leaves. Serve immediately.