Wash the mushrooms and slice them into 0.5 cm thick slices. Peel and finely chop the onion. Chop the parsley finely.
In a frying pan heat up 1 tbsp butter/oil/lard. Fry the mushrooms until they start to brown. Mushrooms loose water quickly, so remove them before they start to "shrink" . Set them aside for later.
Using a further tbsp butter/oil/lard fry the onions. Add the tomato paste just when they begin to brown, and fry for a further minute. The roasted tomato paste will add to the brown colour of the sauce. Deglaze with the stock/broth and cream.
Add the mushrooms back in and season with salt and pepper to taste. Add the thyme, parsley and balsamic vinegar and cook the sauce until you achieve the desired consistency.
If you like the sauce to be thicker, mix 1 tablespoon of cornstarch/corn flour with 2 tablespoons of water to a thick paste. Add to the sauce. Bring the liquid back to a boil. If the sauce is too thick for your liking, you can add more broth.
