Wash the zucchini and grate into long thin spaghetti with a grater. The more spaghetti-like the zucchini strips are, the easier it is to eat the dish afterwards.
Melt the butter in a pan and sweat the zucchini spaghetti briefly. Then add the coconut milk and simmer.
Meanwhile, cook the spaghetti al dente in plenty of salted water. Just before the spaghetti is ready, stir the curry paste and tomato paste into the sauce. Season to taste with salt.
Add the finished spaghetti to the sauce and mix well.