Prepare the vegan meatballs according to the package instructions and keep them warm.

Bring a large pot of salted water to a boil. Cook the whole wheat spelt fusilli until al dente, following the package timing.

Slice the red onion into thin rings. Place the rings in a mixing bowl.

Pour 250 ml of boiling water over the red onion rings. Add the vinegar and let them pickle for 5 to 10 minutes.

Drain the pickled red onion rings and set them aside for serving.

Slice the button mushrooms and finely chop the yellow onion. Reserve about one handful of mushroom slices for the garnish.

Dry-fry the reserved mushroom slices in a frying pan until golden brown. Add 1 teaspoon of cooking oil and fry for 1 additional minute.

Transfer the golden mushroom slices to a plate and set aside. Add the remaining cooking oil to the frying pan if needed.

Sauté the chopped yellow onion in the frying pan until translucent. Add the remaining sliced button mushrooms.

Cook the mushrooms until golden brown and their released liquid has mostly evaporated. Stir regularly to prevent sticking.

Pour 150 ml of vegetable broth into the frying pan. Simmer until the broth has reduced slightly.

Stir in 200 ml of vegan cream. Add the pickled green peppercorns and mustard.

Stir half of the chopped fresh parsley into the mushroom sauce. Simmer gently until the sauce is hot and creamy.

Divide the cooked fusilli, warm vegan meatballs, and creamy mushroom-pepper sauce among three plates. Spoon the sauce over the pasta and meatballs.

Garnish each serving with the reserved golden mushrooms, pickled red onion rings, and remaining fresh parsley. Serve immediately.