1 Rinse orange in hot water, wipe dry and grate about half of the zest finely. Juice orange.
2 Rinse fish, pat dry, season with salt and sprinkle with 1 tablespoon orange juice.
3 Rinse and dry leek, then slice into thin rings. Rinse pumpkin, wipe dry, remove seeds and cut into small cubes.
4 Heat the oil in a non-stick pan. Cook fish on each side for about 1 minute. Remove from pan, season with pepper and set aside on a plate.
5 Fry leek and pumpkin in remaining hot oil while stirring for about 2 minutes.
6 Add remaining orange juice and orange zest and 2 tablespoons of water to the pan. Continue to cook until the liquid has reduced by half, 3-4 minutes.
7 Season vegetables with salt and pepper. Place fish on top, cover and cook over low heat for about 4 minutes.
8 Cut cress from bed, sprinkle over fish and serve.