Cut the cod into 1 1/2 – 2 cm thick slices. Rinse the leeks and cut into rings. Melt the margarine in a low wide pot or oven pan. Sprinkle with curry powder and let it simmer for a minute. Add the leeks and stir. Add the fish and grate the orange zest on top. Add the salt. Add the juice from the orange and finally the water. Allow the fish to simmer about 15 minutes or until it is white and opaque and the leeks are tender. Pour a little of the broth over and serve with boiled potatoes and a salad.