Heat the oil in a large frying pan and fry the onion and garlic with about half the carrot and the beef for 5 minutes until the beef is browned all over
Stir in the tomatoes and ketchup. Crumble in the stock cube, bring to the boil and simmer for 20 minutes, stirring occasionally, until thick
Meanwhile, grate the cucumber and mix with the remaining carrot
To serve, slice the rolls down the centre and open out. Spoon over the meat sauce. Serve immediately with carrot and cucumber sprinkled on top, and with extra ketchup