Prepare burger: Heat a grill pan on medium heat and coat with oil. Cook vEEF patties for 2-3 mins on each side until a golden-brown crust forms. Add mushrooms to pan and grill until caramelized. Add cheese on top of the patties and cover with a heatproof bowl for 3o secs or until melted.
Assemble burger: Build your burger in this order: Bun, mayo, lettuce, tomatoes, patty, mushrooms, pickles, onion, and ketchup.