Place the sa!ron in a bowl, squeeze over the lemon juice and leave to steep.
Bring a saucepan of water to the boil and cook the fregola at a simmer for 8–10 minutes, or according to the packet instructions. Drain and set aside in a bowl, drizzled with the teaspoon of olive oil.
Heat the 2 tablespoons of oil in a medium saucepan that has a lid, add the shallot and fennel, and cook until softened and translucent. Add the fish stock and bring to the boil, then add the clams. Cover the pan and cook until the clams pop open (discard any that do not open).
Stir in the steeped sa!ron, fennel pollen or seeds, fregola and chopped parsley, then season with salt and pepper. Serve in warmed bowls with extra parsley and crusty bread.