Wash and peel potatoes. You have an option to cook and serve them in a separate dish or with the seafood. If serving separately, slice them into 1/4" rounds. Otherwise, dice them. In a pot, cover potatoes with seafood stock, bring to simmer and cook for about 15 minutes until done if serving separately or for 10 minutes if plating with seafood.
*As an option, reserve some diced vegetables (leeks, fennel, carrots, and celery) for this step. They will add more texture to the stew.
If serving lobster tails, clams, or mussels, cook them until done and reserve.
Add bite-size fish pieces in order of how long they will take to cook. Monkfish and sea bass will take a few minutes longer than the rest of the fish, so start with them. When ready to serve, taste and adjust seasoning. Garnish with freshly chopped parsley and fennel fronds or other herbs of your choice.
Traditionally, French restaurants serve bouillabaisse not plated letting the guests assemble their dishes right before eating — large dishes with cooked seafood, fish stock, rouille, and baguette toasts. Each eater places some seafood and potatoes in a bowl, adds some stock, spreads some rouille on a couple of toasts and places them on top of the stock to soak flavorful essence of bouillabaisse. Other restaurants prefer serving it as a dinner that consists of 3-4 plated dishes featuring different kinds of seafood and making sure all components are distributed evenly. Either way, this fish stew is fantastic! Bon appetite!