Wash, dry and chop the mushrooms as needed. If they are small, you can leave them whole. Chop the onions and put to fry in the heated oil.
Optionally, add 2 cloves of diced garlic. Once softened, add the mushrooms and stir gently for 2-3 minutes. Top up with the wine and stir until the alcohol evaporates. Allow the mushrooms to sauté until softened.
Add spices to taste and leave the dish uncovered for all the liquid to evaporate. Serve the stewed mushrooms with onions as a side dish to meat, vegetable dishes.