Heat the oil in a casserole dish. Brown the pork for about 10 mins until golden all over, stir in the tomato purée and cook for 1 min. Pour over the chicken stock, then add the strips of orange zest and juice, cinnamon and thyme. Bring to the boil, reduce the heat, then cover and simmer for 1½ hrs.
Meanwhile, make the sauce. Heat a non-stick frying pan and dry-fry the onions and whole garlic cloves for about 5 mins, turning often until softened and lightly charred all over. Tip into a blender. Add the tomatoes to the pan. Cook for 3 mins until starting to blister and char, then tip into the blender. Add 1 tbsp oil to the pan. Fry 1 of the tortillas for 1 min on each side until golden. Tear into pieces and tip into the blender. Adding more oil if you need, fry the almonds for 3 mins until golden. Add to the blender. Finally add the raisins, coriander and cumin to the pan and cook for 1-2 mins until the raisins are plump. Add these to the blender along with the chipotle paste and finely chopped chocolate. Whizz together until a rough paste forms.
Using a slotted spoon, remove the meat from the pan to a board, leave to cool a little, then use forks or your fingers to tear into shreds. Remove the cinnamon, orange zest and thyme sprigs from the pan and discard. Pour a little of the cooking liquid into the blender, then carefully whizz together with the mole sauce. Tip sauce into the pan with the rest of the pork cooking juices. Simmer on the hob for 10-15 mins, then return the shredded pork to the pan and cook for 20 mins more. Season to taste. Can be made up to this point up to 2 days in advance and stored in the fridge or frozen for up to 3 months.
Just before serving, microwave the tortillas for 1 min to warm them. Toss together all the salsa ingredients and season well. Set everything out on the table. To serve, spoon some of the pork mole onto a tortilla, top with some salsa, then roll up and eat.