Cook the pasta until al dente according to the instructions on the packet.
Peel and grate the carrots. Peel the onion, chop it finely and toast it a little in hot margarine or oil. Stir in the grated carrots and roast a little more. When the carrots have cooled, stir in the yogurt, salt and mint.
Strain the pasta and place on a plate. Carefully stir in the carrot sauce. Serve hot.