Remove the fillet from the nohu, be sure to remove all the bones and slice the fish into 1-inch medallions. Reserve the scraps for the soup. In a soup pot, saute the fish scraps and the small popaa in the olive oil over high heat. Add the chopped onions, tomatoes, bouquet garni, garlic cloves, water, salt, pepper, cayenne pepper, and saffron. Bring to a boil for 5 minutes, then simmer for 1 hour.
Put the soup on low heat add the potatoes and poach for 5 minutes. Add the nohu medallions in the soup and poach for 5 more minutes.
In a mixing bowl, combine the garlic puree with the egg yolks, salt and pepper. Add the oil very slowly and whip continuously to get a mayonnaise consistency.
Serve the soup in individual soup plates with the fish medallions, the potatoes and the aioli, also called a "rouille", and croutons on the side.