Cream of Carrot Soup with Orange and Smoked Mackerel

With a sharp knife, cut off peel and bitter white pith from oranges. Quarter lengthwise and cut crosswise into slices. Peel and thinly slice carrots. Peel and finely chop onions. Melt butter in a saucepan. Add sugar and cook until melted. Add carrots and onions and cook, stirring, 2-3 minutes. Add oranges, wine, broth and orange juice. Bring to a boil, cover, and simmer about 30 minutes. With a ladle, remove some of the carrots and oranges. Set aside. Purée remaining soup. Stir in cream, bring to a boil again and season with mustard, salt, and pepper to taste. Separate mackerel fillets into bite-sized pieces. Cut chives into about 3 cm (approximately 1 inch) long pieces.