Heat the remaining oil in the same pan and add the chorizo and chopped onion. Cook for 5 minutes or until the onion has softened. Add the red pepper and cook whilst stirring for 2 minutes. Add the garlic and paprika and cook for 1 minute or until fragrant. Add the flour and cook for 1 minute whilst stirring until coated all over. Add the chopped tomato and chicken stock, stirring until well combined. Season with black pepper before transferring to slow cooker.