Heat oven to 200C/180C fan/gas 6. Put the fish in a shallow ovenproof dish and pour over half the lime juice, with a little of the zest, then grind over some black pepper. Bake for 8 mins or until the fish flakes easily but is still moist.
Meanwhile, put the rest of the ingredients, plus the remaining lime juice and zest, in a bowl and combine well. Spoon onto plates and top with the cod, spooning over any juices in the dish.