1. Heat the oil in a large saucepan over a medium heat, then brown the chicken all over - in batches if necessary. Remove with a slotted spoon and set aside. Add the onion and garlic to the pan and cook for 3-4 minutes, stirring frequently, until softened and lightly browned.
2. Add the chorizo and cook for 3-4 minutes, stirring occasionally. Add the wine and reduce by half. Stir in the tomatoes, thyme, bay leaves, stock and sugar. Return the chicken to the pan and push under the sauce. Cover and cook for 20 minutes.
3. Stir in the potatoes and olives and cook for a further 35 minutes. Remove from the heat and season and garnish with thyme leaves.