Mix the beef with the herbs and seasoning. Divide into 24 and roll into balls. Heat the oil in a large frying pan and fry the meatballs for 10 minutes until golden.
Add the chopped tomatoes and purée and cook for a further 10 minutes.
Warm the tortillas according to pack instructions. Spoon the meatballs over the tortillas, sprinkle over the cheese and add a dollop of soured cream.