Method

1. Cook the pasta in a large pan of salted boiling water until al dente. Reserve a cup of pasta water, then drain.
2. Meanwhile, heat the olive oil in a large frying pan over medium heat. Add the garlic (and onion, if using) and sauté for 2–3 minutes until fragrant.
3. Stir in the harissa paste and cook for 1 minute. Add the tomatoes, season with salt and pepper, and simmer for 10–15 minutes until thickened.
4. Add the olives and capers, and cook for 2–3 minutes more. Adjust seasoning to taste.
5. Toss the drained pasta with the sauce, adding a splash of reserved pasta water if needed to loosen.
6. Serve topped with fresh herbs, a squeeze of lemon, and a drizzle of olive oil.