Tear off 4 large sheets of foil and line with nonstick baking paper. Place 2 fish fillets on each piece of baking paper, then scatter over the lemon rind, capers and spring onions and season with salt and pepper. Fold over the paper-lined foil and scrunch the edges together to seal. Place the parcels on a large baking sheet.
Put the tomatoes in an ovenproof dish with the beans, garlic, anchovies, oil and lemon juice. Season with salt and pepper and mix well. Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 10 minutes until the tomatoes and beans are tender.
Place the fish parcels next to the vegetables in the oven and bake for a further 8–10 minutes until the flesh flakes easily when pressed in the centre with a knife.
Spoon the vegetables on to 4 serving plates, then top each with 2 steamed fish fillets. Garnish with the chopped parsley and caperberries, and serve immediately.