How to Make It
In a small bowl, combine the vinegar with the sugar, cucumbers, 1 teaspoon of the ginger and 1/2 teaspoon of salt. Set aside.
In a medium saucepan, combine the rice with 1 1/3 cups of water and bring to a boil. Cover and cook over very low heat until tender, 20 minutes. Remove from the heat and let stand for 5 minutes, then fluff with a fork.
Meanwhile, in a nonstick skillet, heat 2 tablespoons of the vegetable oil. Add the garlic and shiitake, season with salt and cook over high heat, stirring, until browned, 6 minutes; scrape onto a platter. Heat 1 tablespoon of the vegetable oil and add the tofu. Cook over high heat, turning, until browned, 5 minutes. Scrape the tofu onto the platter, keeping it separate from the mushrooms.
Heat 2 tablespoons of vegetable oil in the skillet. Add the remaining 1 teaspoon of ginger and stir-fry for 30 seconds. Add the mustard greens and sesame oil, season with salt and cook until the greens are wilted and just tender, 4 minutes. Add the greens to the platter. Wipe out the skillet. Heat the remaining 1 tablespoon of vegetable oil in the skillet. Add the zucchini and cook over high heat until softened, 3 minutes. Add the kecap manis and cook until the zucchini is glazed, 1 minute; scrape onto the platter. Keep warm.
Mound the rice in bowls and arrange the cooked vegetables in separate piles. Using a slotted spoon, add the pickled cucumbers to the bowls. Garnish with the scallions and a dollop of gochujang and serve.
Gochujang is available at Korean markets or from hmart.com.