Blitz in a food processor, adding liquid as needed. The texture should not be too runny.
Form into burgers on a nonstick pan lined with unbleached baking paper/silicon mat.
Refrigerate to firm up at least a couple of hours or longer if it's more convenient.
Bake (depends on your oven, mine takes about 20 minutes each side at lowish temp). If they lose shape when you flip them over, just squish them back into a burger shape and use less liquid next time.