- In a large pot of salted boiling water, cook the pasta al dente. Set aside ½ cup (125 ml) of the cooking water for the sauce. Drain the pasta.
- Meanwhile, in a large skillet over high heat, soften the onions and garlic in the oil. Add the harissa paste and cook for 1 minute, stirring constantly. Add the tomatoes and olives. Season with salt and pepper. Let simmer for 15 minutes. Add the shrimp and simmer for 2 to 3 minutes or until the shrimp are cooked through. Keep warm.
- Add the pasta to the sauce and stir well. Add cooking water to thin out the sauce, if needed. Adjust the seasoning.