Cook the pasta in plenty of salted water (approx. 1 teaspoon per litre) in a large pot until al dente (approx. 1 1⁄2 minutes).
Peel and chop the onion. Clean or peel and wash the vegetables. Dice sweet potatoes and parsnips. Cut sugar snap peas into pieces. Cut tomatoes into quarters. Heat the oil in a wide saucepan.
Fry the onion, sweet potatoes and parsnips until golden brown. Fry the mangetouts and tomatoes briefly. Add orange juice and cream, add cardamom. Reduce the sauce for about 10 minutes.
Peel oranges so that the white skin is removed. Cut oranges in half, then cut them crosswise into slices. Add oranges to the vegetable sauce. Season with salt and pepper. Drain the pasta and mix into the sauce.
Sprinkle with parmesan and pistachios.