Thaw the shrimp. Peel the asparagus and cut into bite-sized pieces. Bring the water to the boil, dissolve the mushroom bouillon in it and blanch the asparagus pieces in the broth for 3 minutes. Wash the tomatoes and blanch them in the broth for 12 seconds to peel them. Rinse in cold water, peel, quarter lengthways, remove the green-white stem and the grains. Cut the quarters lengthways into strips approx. 5 mm wide.
Put the pasta in the boiling broth and cook al dente according to the instructions on the package. Strain the pasta and keep 50 g of the pasta water ready.
Fry the tomatoes in the olive oil in a sufficiently large pan for 2 minutes. Add the pasta and fry for 2 minutes. Mix the sour cream with the remaining ingredients for the sauce and pour over the pasta. Let it simmer briefly, then reduce the heat supply. Add the asparagus pieces, the prawns and the cherry tomatoes. Sprinkle with Parmesan and grind a pinch of black pepper over everything. Serve in the pan.