Pre-heat a griddle or frying pan. Peel the flat mushrooms, remove the stalks and flatten with the palm of your hand.
Once the griddle/frying pan is hot add the vegan halloumi cheese and the mushrooms and cook for 2-3 on each side
Toast the bread on both sides
To assemble, place one slice of toast on a plate and top with the pickled red cabbage, followed by a lettuce leaf and the sliced tomato. Top with the cooked cheese, then mushrooms and finally add the raw red onion and remaining lettuce. Place the second slice of toast on top and serve straight away