Cook pasta according to directions. Make sure to add salt to the pasta water.
Heat olive oil in a pan on medium heat and add sliced onions. Add salt.
Stir the onions every five minutes or so. Cooking will take about 35-40 minutes. If the onions start to stick, add a little water, like a quarter of a cup or so. Add the balsamic vinegar the last 5 minutes.
Add sliced mushrooms and pepper. Cook until tender. Add the red wine and cook a few more minutes, until wine is cooked down. Serve over cooked pasta.
Top with nutritional yeast and serve.
Notes
This onion mushroom pasta recipe will last 5 days in an airtight container in the fridge.