Put avocado or olive oil in a large skillet over medium-high heat. Saute the shallots, stirring occasionally, until they're translucent. Lower the heat to medium if necessary.
Stir in the vegan butter or oil and mushrooms. Cook until most of the liquid has evaporated. Remove from the heat and let it cool for 5-10 minutes.
Put the mushrooms mixture in a food processor and process for 1 minute. Add salt, pepper, walnuts, balsamic and truffle oil and process until smooth.
Put the paté in a container or jar, seal and store in the fridge for minimum 30 minutes. Serve with a good sourdough bread or crackers.
Notes
*You can use other mushrooms such as baby Portobello but don't use shiitakes, they will make your paté too rubbery (from experience).