Preheat oven to 170°C. Place a casserole over a medium high heat. Mix the beef with some olive oil and fry in batches for 6 minutes or until coloured. Place all of the meat back in the pan and add the onion, bay leaves, smoked paprika, chilli flakes and garlic and cook for 1 minute.
Add the stock and tomatoes and bring up to the boil. Cover, and place in the oven for 2 hours or until the meat is tender.
Add the black beans and cook, covered, for a further 15 minutes. Season to taste with salt and pepper and shred beef using two forks.
Meanwhile grill the corn until slightly blackened, cool and remove kernels. To make the salad take the corn and gently toss through avocado, cheese, coriander and lime juice.
When ready to serve prepare tortillas to packet instructions and top with beef and some salad.
For a less spicy version, try ¼ tsp dried chilli flakes or simply omit them.
Tinned black beans are often found in the Mexican food section of your supermarket, rather than with the other tinned beans.