Cut potatoes into 5mm thick slices and lay in an ovenproof dish. Drizzle with olive oil, salt and pepper. Bake at 200°C for 20 minutes until almost cooked. Combine tomato, spring onions, olives, basil, capsicums and 1 tablespoon olive oil together and season to taste. Place each piece of fish in the centre of a piece of baking paper or foil and top with tomato mixture. Wrap tightly to enclose and, if using baking paper, tie with string. Position parcels on top of potatoes and bake 10 minutes until just cooked. Place partially opened fish parcels on each plate and serve with potatoes and a crisp green salad.