How to Make It
Bring a saucepan of salted water to a boil. Fill a small bowl with ice water. Blanch the parsley stems in the boiling water until they turn bright green, about 30 seconds. Using a slotted spoon, transfer the stems to the ice water, then drain and pat dry. In a small bowl, drizzle the parsley stems with a little olive oil to keep them moist.
In a large, deep skillet, heat the 1/4 cup of olive oil. Add the minced garlic and cook over moderately high heat until fragrant, about 2 minutes. Add the water and bring to a boil. Add the clams, cover and cook, shaking the skillet a few times, until the clams open, about 5 minutes. Using a slotted spoon, transfer the clams to a plate, leaving their juices in the skillet.
Season the cod fillets with salt and pepper. Add the fillets to the clam juices in the skillet. Cook over moderate heat, turning the fillets once, until the flesh is white throughout, about 8 minutes.