Make a stock and add toasted tortillas - what could be simpler? Toasted tortillas have a lovely nutty flavour and soak up the broth. We've charred the onion for extra flavour and added a hint of cinnamon by pouring hot water over half a quill to extract a faint spice note. In summer you could also add some diced tomatoes. This style of tortilla soup, with the addition of citrus, is traditionally served in Mexico's Yucatán Peninsula. Add orange and lime together to suit your taste here.