Bouillabaisse is a traditional fish soup that originated from the port city of Marseille, France. Usually, the ingredients in a bouillabaisse vary based on the catch of the day. However, there are some commonly used ingredients in a bouillabaisse, which include fish such as red snapper, sea bass, or monkfish, shellfish like mussels, clams, or shrimp, vegetables such as potatoes, leeks, onions, fennel, and tomatoes. Other ingredients could include herbs such as saffron, garlic, thyme or rosemary, and olive oil. The dish is typically served with crusty bread and rouille, a mayonnaise-like sauce made with garlic, saffron, and olive oil.