Thai Bouillabaisse

Tips: Lemongrass is an aromatic tropical grass used to add a pungent, lemony flavor to Asian dishes. It is available fresh at large supermarkets and Asian groceries.

Shrimp is usually sold by the number needed to make one pound. For example, “21-25 count” means there will be 21 to 25 shrimp in a pound. Size names, such as “large” or “extra large,” are not standardized. In recipes calling for a specific count, order by the count (or number) per pound to be sure you're getting the size you want.

To peel shrimp, grasp the legs and hold onto the tail while you twist off the shell. Save the shells to make a tasty stock: Simmer, in enough water to cover, for 10 minutes, then strain. The “vein” running along a shrimp's back (technically the dorsal surface, opposite the legs) under a thin layer of flesh is really its digestive tract.

To devein shrimp, use a paring knife to make a slit along the length of the shrimp. Under running water, remove the tract with the knife tip.

Be sure to buy “dry” sea scallops (scallops that have not been treated with sodium tripolyphosphate, or STP). Scallops that have been treated with STP (“wet” scallops) have been subjected to a chemical bath and mushy and less flavorful.

To scrub mussels, hold under running water and use a stiff brush to remove any barnacles. Discard any mussels with broken shells or any whose shell remains open after you tap it lightly.