Heat the oil in a large pan over a medium heat. Add the sliced chorizo and red onion and cook for 2 minutes, until slightly crisp. Reduce the heat and add the garlic, tomatoes, chickpeas, chicken stock and seasoning and bring to the boil. Reduce the heat and simmer for 12 to 15 minutes, stirring occasionally. Remove from the heat and add the chopped parsley.
Ladle the soup into serving bowls and serve immediately with some crusty bread.