Clean the mushrooms, leave the small ones whole, cut the larger ones in half. Mix white wine, salt, pepper, lemon juice, thyme, bay leaf, coriander (mash a little beforehand with a wide knife or mortar), pour over the mushrooms and let it steep for approx. 1 hour.
Let the chopped onions and garlic, squeezed through the press, turn light brown in the oil, then add the mushrooms and marinade. Warning: when it starts to boil, there will be a large amount of liquid in the pan. Reduce this by boiling in an open pot until there is only about the amount of a salad marinade left. Then mix in the skinned, pitted and cut tomatoes and let them steep for a short time. Finally fold in the parsley.
If it tastes lukewarm as well as cold, you can prepare it several days in advance.