Rouille
I have always thought that the best part of fish soup is the rouille, a peppery, garlicky sauce that is slathered on toasted rounds of baguette and floated on the surface of the soup. I also like to stir some rouille into the broth. Similar to the Provençal aioli, a garlic-flavored mayonnaise, rouille is flavored with hot pepper and saffron, which give it its signature rust color. (Rouille literally means “rust” in French.) Today I have noticed that North African Jews often spice up their rouille even more, by adding a little harissa (see page 33) to it. Traditionally, a mortar and pestle are used to pound the garlic, pepper, and egg yolk, gradually incorporating the oil to make a mayonnaise. Today it is easy to put everything in a food processor and slowly add the oil, drop by drop. Leftover sauce is good on sandwiches or as a dip.