Peel and finely dice the onion, beetroot and garlic. In a large pan, first sauté the onions with a dash of olive oil over a medium heat. After 1-2 minutes, add the garlic and beetroot. Sauté for a further minute, deglaze with the port wine and reduce. Only then add the cream and thyme and allow everything to simmer gently for approx. 15 - 20 minutes.
In the meantime, cut off the ends of the mushroom stalks. Then cut the mushrooms into large, bite-sized pieces. Fry them in a small pan over a high heat. When they are lightly browned, add a dash of olive oil, season with salt and set aside in the hot pan.
In the meantime, cook the pasta in salted water until al dente according to the packet instructions. When draining, collect approx. 50 ml of the pasta water and add to the beetroot sauce. Add the juice and zest of the lemon. Flavour with yeast flakes, salt and pepper.
Mix the pasta with the sauce and serve sprinkled with the fried mushrooms and a little grated vegan cheese, if desired.