Heat up the olive oil in a large enameled cast iron or stainless steel saute pan over medium flame. Add the onion to the pan and cook until it starts to get some color all over, making sure not to burn it, about 10 minutes or so.
Add the wild mushrooms to the pan with a pinch of sea salt and give them a nice stir ( the salt will help bring out the moisture from the mushrooms). Pour in the wine and allow them to cook uncovered until almost all the liquid has evaporated into a nice thick wine sauce.
Add this point you can add another splash of wine and with a spatula scrape all the brown bits from the bottom of the pan. This step is optional. Adjust seasonings with the sea salt, add the black pepper to your taste and serve as a side dish or a topping for burgers, chicken or roasts.