Preheat a non-stick frying pan and fry the bacon for 3 minutes. Remove from the heat and finely chop. Place in a large bowl with the beef mince, seasoning and beef stock cube. Season with black pepper and then bring the mixture together in your hands. Divide into four and shape into 8 - 10 cm round patties.
Cook the burgers for 15 minutes, turning them over occasionally. Cover the burgers with a large saucepan lid halfway through cooking time, to help keep them moist. Check the burgers are cooked through and no pink remains. Remove from the heat and keep warm, whilst you prepare the buns.
Cut each bun in half and brown the cut sides in the frying pan. Sear the buns for a few minutes. Remove from the pan and fill each bun with lettuce, burger and two slices of tomato.