Mist a large pan with spray oil and brown the meat all over (you may need to do this in two batches). Transfer the browned meat to the slow cooker, then add the onion to the pan and cook for 5 minutes, until browned and softened. Add the garlic with the chilli flakes, cumin and paprika and cook for 1 minute, until fragrant.
Add this to the slow cooker with the chopped tomatoes, ale, beef stock, kidney beans, peppers, dried mixed herbs, bay leaf and tomato puree. Put the slow cooker on a low setting for 7-8 hours covered with the lid until the beef is completely tender.
Towards the end of cooking, preheat the oven to 180°C/gas mark 4. Cut the tortillas in half then cut each of these halves into 8 triangles. Spread these over a large baking sheet and sprinkle over smoked paprika. Bake for 8-10 minutes until crisp, then leave to cool.
Once the beef has finished cooking, place a colander over a wide saucepan and transfer the chilli to this, allowing all the liquid to fall in to the saucepan. Place the meat and vegetables in the colander over a bowl to catch any further liquid.
Place the saucepan with the liquid over a high heat and reduce for 10 minutes so that it goes down by roughly half. Add the meat back into the pan and warm through, then divide between 4 bowls. Divide the tortillas and add the sliced jalapeños, chopped coriander and soured cream to serve.