Heat 2 tablespoons of the oil in a saucepan, add the onion and cook for 3 minutes, stirring often. Add the garlic and cook for 2–3 minutes or until softened. Stir in the tomato purée, tomatoes and chipotle paste or sauce. Simmer for 20 minutes, adding a little water if needed, then season.
Meanwhile, rub the remaining oil over the chicken breasts and season well. Heat a griddle pan until smoking, add the chicken and cook for 7 minutes on each side or until lightly charred and cooked through. Alternatively, cook under a preheated hot grill.
Cook the pasta in a large saucepan of salted boiling water according to the pack instructions until al dente. Drain, reserving a little cooking water. Stir through the tomato sauce, adding a little cooking water to loosen if needed.
Cut the chicken into bite-sized pieces and stir through the pasta. Spoon into serving bowls, sprinkle with the coriander and serve with dollops of soured cream.