1. Combine the sour cream, mayonnaise and sweet mustard. Season to taste with salt, pepper and sugar. Add the cabbage and carrots and stir until everything is covered. Let stand for about an hour.
2. Form the ground beef into 4 patties of approx. 4½ ounces each and season well with salt and pepper. Brown the patties in some oil on each side.
3. Brush the patties with a generous amount of barbecue sauce. Pop them in the oven for 6-8 minutes at 400°F. Then top with Burger Blue cheese and give them another couple of minutes until the cheese has melted.
4. Warm the buns. Place a spoonful of coleslaw on the bottom half of the bun. Then add a patty and a slice of tomato and finish off with the top half of the bun spread with barbecue sauce.