Caramelized Onion and Mushroom Sandwich Recipe (with Video)

Preparation of onions and mushrooms
1. Peel and thinly slice the onions.
2. Heat some olive oil in a pan and add the onions with salt to release their liquids.
3. Cook the onions on medium-low heat for around 30 minutes, until they become dark and sticky.
4. In another pan, sauté the sliced mushrooms with garlic until they are nicely seared.
5. Add lemon juice and season with salt and pepper.
Assembling the sandwich
1. Toast the sourdough bread in a pan with some olive oil.
2. Spread one slice with truffle spread (if desired), add the mushrooms, parsley, and caramelized onion, and top with vegan cheese.
3. Toast for a few minutes until the cheese has melted.