Heat the oil in a large frying pan, add the onion and chorizo and fry, stirring, until the onion is pale golden. Stir in the garlic, peppers and tomatoes and cook for 2–3 minutes until just softened.
Toss the rice in with the vegetables, then mix in the paprika, saffron, chicken and about half the stock. Bring to the boil, stirring, then cover and simmer for about 20 minutes, topping up with remaining stock as needed.
Stir in the peas and olives and cook until the peas are cooked. Sprinkle with parsley, if liked, and spoon into bowls.