In cioppino, a savory and aromatic concoction, crab, shrimp, clams and firm-fleshed fish - indeed any seafood in profusion - are combined with onions, … Add the shallots and cook until soft and translucent, about 5 minutes. How to make Cioppino Begin by heating 4 tablespoons of the oil over medium heat. Add the garlic and for 1 minute more.