Put the thinly sliced onion in a bowl. Squeeze over the lemon juice and add a pinch of salt. Massage the juice into the onions then set to one side.
Combine the vegan butter with the spices, mixing vigorously to make sure it’s all fully mixed through, place into the fridge.
Heat a frying pan over a medium high heat. Add the quartered mushrooms and fry until all the moisture has evaporated, this should take around 7-8 minutes. Once the mushrooms have taken on some colour, reduce the heat to medium low, add a sprinkle of salt and the spiced butter and fry until aromatic, around 2 minutes.
Set the mushrooms aside while you grate the tomatoes. Add a small pinch of salt to the pulp and leave in a sieve to remove excess moisture.
Just before serving, mix the sumac and parsley into the pickled onions.
Spoon the hummus into a bowl then top with the mushrooms, sumac pickled onions, tomato pulp and a pickled chilli for good measure. Enjoy with fluffy pittas/bread!
