Heat the oil and fry the onions in it over medium heat until they are soft and golden. This takes about 10-15 minutes. When they`re almost done, add the garlic and cook a little more.
Season with cinnamon, coriander, nutmeg, cardamom, salt, pepper, chilli and lime juice, mix well and set aside.
In the meantime, cook the pasta.
Mix the yogurt with salt, pepper and sumac. Finely chop the mint.
To serve, divide the pasta on two plates. Pour the yoghurt over it, then sprinkle the onion mixture and finally the mint. When there is some oil left, drizzle over the dish and serve.