Thinly slice the onion and bell pepper, then chop the garlic.
Heat the oil in a large, shallow saucepan and gently sauté the onion and pepper for about 8-10 minutes, until soft.
Add the garlic and marjoram, stir for a minute, then add the drained beans, lemon juice and zest. Add a splash of water too, if it looks too dry. Season to taste. Put a lid on and cook for another 5 minutes.
Meanwhile, heat the grill in your oven or heat a griddle pan.
Mix the paprika and chickpea flour. Add a large pinch of salt and mix again.
Coat the fish with this mixture, then spray with oil and grill for 5-8 minutes, until golden - don’t overcook the fish!
Serve the fish on top of the beans, with fresh herbs scattered over it.