Place the chickpeas, spring onions, garlic, parsley, spices, harissa, lime rind and juice and flour in a blender or food processor.
Season with salt and pepper and blitz until fairly smooth.
Using your hands, shape the mixture into 4 patties, then chill for 20 minutes.
Meanwhile, make the salsa.
Mix together all the ingredients and set aside.
Heat the sunflower oil in a frying pan and cook the burgers for 3–4 minutes on each side until lightly golden and heated through.
Serve with watercress and the salsa.