Step 1

Heat the olive oil and butter together in a large skillet.

Step 2

Add in the onions and start frying. Fry for 5 minutes to get them started then add in the mushrooms.

Step 3

Fry until the mushrooms have reduced in size and lost their moisture and the onions are softened completely.

Step 4

Add in the garlic and saute until browned and fragrant.

Step 5

Stir in the balsamic vinegar and wine and cook another 2 minutes, making sure to delgraze the bottom of the pan ( scrape off any browned tasty bits so that it goes into the sauce!)

Step 6

Season to taste with salt and pepper and serve!