Heat the oil in a large, heavy-based saucepan. Add the onion and chorizo and cook for 2 minutes or until the onion has softened and the chorizo is lightly browned.
Stir in the garlic, then add the tomatoes, stock and saffron, and season to taste. Bring to the boil, add the chicken and red pepper and simmer for 10–12 minutes or until the chicken is cooked through.
Add the rice and peas and cook for 2–3 minutes until heated through. Ladle the soup into bowls and serve.