Begin with the broth. Combine all broth ingredients together in a large pot and simmer over low−medium heat for 25 minutes. Skim the broth and pass though chinois to produce a smooth, velvety texture.
For Spicy Rouille
While the broth cooks, prepare the spicy rouille by whisking together egg yolk and garlic first, then add olive oil, saffron, salt, cayenne pepper, and Sriracha. Cover and refrigerate to set.
For Seafood, Vegetabes, and Assembly
- For the seafood, heat ¼ cup olive oil in a large (6-quart) saucepan over medium-high heat. Sear scallops for 2−3 minutes (depending on size) until scallops are nicely browned, then remove them from pan, reserving pan.
- If incorporating clams and mussels, steam them for 5−7 minutes until they open. Discard those that don’t open.
- In the same saucepan used to sear the scallops, add the finished broth and bring to a boil.
- Add all vegetables and udon noodles to the pan. Sauté together until the vegetables are semi-cooked yet still crunchy (about 5 minutes).
- Remove pan from heat, then add crushed garlic (more or less to taste), freshly ground pepper, butter, and lemon and lime juices. Gently incorporate the scallops and any other shellfish, and simmer until noodles are soft and scallops are cooked through.
- To serve, place a thick slice of crusty French bread into a soup bowl (fresh or slightly toasted) and top with generous spoonful of rouille. Ladle the fragrant vegetable-scallop bouillabaisse broth mixture over the bread. Bon appétit!