Place the chipotle, onion, garlic, coriander stalks, tomatoes and spices into a blender and blend until smooth.
Heat a splash of oil in a large pot and add the pureed tomato mixture. Add a good pinch of salt and pepper and cook, stirring regular for 3-4 minutes. Add the chicken and coat in the mixture then add stock. Bring to the boil and then turn down to a simmer. Cover and cook for 35-40 minutes.
Meanwhile, fill a pan with 2cm of oil. Over a medium to high heat add the tortilla strips, in batches, and fry for about minute, or until golden and crisp. Remove with a slotted spoon and drain on kitchen paper.
Remove chicken from the soup and shred meat. Discard the chicken skin and bones and return meat to the soup. Check seasoning it may need a little extra salt. Add half the lime juice.
Portion soup between bowls and top with fetta, tortillas chips, fresh coriander and a little extra lime.