Cut the vegetables - The onion/leek to small cubes, the cabbage to strips, the carrots to thin strips, and the mushrooms to reasonable sizes.
In the meantime heat a pot of water for the noodles.
In a pan or wok heat a bit of oil over low heat and add the onion/leek
When the onion/leek begins to become translucent add the mushrooms turn the heat to medium-high, and cook until they lose all their water.
When the mushrooms finish losing their water add the rest of the vegetables. The vegetables should cook for around 10 minutes. After around 8 minutes add the sauce and stir.
To have the noodles ready in time for the vegetables add them to the water so they will be ready with the vegetables (i.e. if noodles cook time is 4 minutes, add them to the pot 6 minutes after adding the vegetables to the pan). Cook time for the noodles should be written on the package.
When the noodles are ready, rinse them and add them to the pan. Stir until everything is fully coated.
Place on a dish and sprinkle with crushed peanuts - serve immediately.