Soupe de poisson has the same taste as bouillabaisse, but the soup is strained and pasta is cooked in it to give a light liaison. If you are making the soup on the Mediterranean, you will come home with dozens of tiny, freshly caught fish all colors of the rainbow. Elsewhere, use whole fish, fish heads, bones, and trimmings, shellfish carcasses, or just bottled clam juice.
Cook the onions and leeks slowly in olive oil for 5 minutes or until almost tender but not browned.
Stir in the garlic and tomatoes. Raise heat to moderate and cook 5 minutes more.
Strain the soup into the saucepan, pressing juices out of ingredients. Correct seasoning, adding a bit more saffron if you feel it necessary. Stir in the pasta and boil for 10 to 12 minutes or until tender. Correct seasoning again.