Cut the onion and carrots into small cubes. Sweat the cubes in a little oil in a wok or saucepan (pasta will have to be added later). Caramelize with a pinch of sugar. Add the red curry paste to the onion and carrot mixture and sweat a little. Deglaze with the tomatoes. Stir in the vegetable stock and soy sauce. Reduce the heat a lot and put a lid on. Let the carrots simmer gently for about 10 minutes, until the carrots are cooked but still firm to the bite.
During this time, cook the pasta according to the instructions on the package. Then pour off the pasta water and add the drained pasta to the sauce in the wok or saucepan. Mix together with some fresh chopped parsley.
Season to taste with soy sauce and pepper before serving.