Heat the oil in a large heavy-based pot over medium-low heat.

Add the garlic and lemon zest and sizzle for a few seconds.

Add the tomatoes and wine, bring to the boil, then reduce the heat and simmer until liquid has reduced and is aromatic (5 minutes).

Add the shellfish, cover the pot tightly with a lid and cook for 3–4 minutes, lifting the shellfish out of the pot and into a bowl as they open.

Discard any shellfish that remain closed and set the pot aside (you’re going to use this broth shortly).

Remove the meat from half of the shells, discard the empty shells, and reserve the meat in a bowl with the cooked whole shellfish.

The shellfish and cooking liquid can be prepared ahead to this point an hour or two before serving and chilled until needed (just transfer the shellfish broth into a smaller container to fit in your fridge).

When ready to serve, cook the pasta in plenty of salted water for 3 minutes less than the packet instructions.

While the pasta cooks, return to the large pot with the shellfish broth. Bring to a boil.

When the pasta is ready, drain and add to the hot shellfish broth.

Stir through the harissa and return to a boil over a high heat until the pasta is just al dente (2–3 minutes, it should still have a bit of bite).

Add the reserved shellfish, cover and heat through for about 1 minute.

Stir through the parsley, lemon juice, and season with salt and pepper to taste. Serve family style out of the large pot.

The cooking time given in this recipe is for small shellfish such as cockles or pipis. If using larger shellfish, such as green-lipped mussels, adjust the cooking time to 7 minutes.