Preheat the oven to 180°C.
Slice the pepper into long strips. Slice the onion into thin wedges.
Toss these with half of the olive oil and spread them out evenly in a roasting tray. Season with salt and pepper.
Bake in the oven for about 10 minutes until the vegetables are softened.
Meanwhile cut the lemon into half. Put one half aside and cut the other into 3 thick rounds.
Lay these on top of the roasted vegetables and add the garlic.
Put the fish on top, brush with some oil then season with salt.
Bake for another 15 minutes then turn over the fish and scatter the olives and the pine nuts around.
Bake for a further 5-10 minutes until the fish is cooked through.
Squeeze the remaining lemon over the fish & veggies and serve with the parsley scattered on top.