Put the cauliflower florets and mushrooms into a blender and whiz until you get a coarse crumble. Add the remaining ingredients and pulse until you get a slightly sticky mixture. Divide the mixture into equal amounts and create patties between your palms.
Heat some oil in a frying pan.
When hot, dip the patties in some chickpea flour (optional), then fry them for about 3-5 minutes on each side.
Meanwhile lightly toast a few buns, cut in half.
Serve the patties in the toasted buns with condiments, toppings, salad of your choice etc. Alternatively, serve with chips, sweet potato fries and/or or a salad.