While heating the barbecue, soak the raisins in some warm water.
Then mix the meat, onions, eggs, and breadcrumbs and stir well.
Take the mixture and make it into 6 firms, round patties. With your fingers, make a hole in the center of each burger and fill the hole.s with cheese. Try to get an even amount into each burger.
Take the raisins and put an equal quantity into each burger, adding them to the cheese.
The tricky part is to cover the whole burger using the surrounding meat.
Carefully brush the melted butter on the burger and add salt and pepper to taste.
The barbecue should have heated too high, so it is time to oil the grate.
Put the burgers on to cook. Most people like them done 3 to 4 minutes on each side, although I prefer a little less cooked.
Lightly coat the inside of the buns and put them on the grill to toast very slightly. They will soon become too hard if you over-toast them, so be careful.
When you serve them, add a large slice of tomato, and you have a delicious burger.