Place ground beef in a large bowl and gently mix in the steak sauce, wine,garlic powder, bread crumbs, rosemary, parmesian and worchestishire sauce.
Pat the meat into 4 to 6 burgers, just firmly enough that the patties will not fall apart on the grill. Cover with plastic and chill in refrigerator till grill is ready.
Light the grill (propane or wood burning) and allow temperature to reach 400 degrees F. Grill the burgers over a high flame for a minute or so on each side, just long enough to char the outside. Lower heat (or move burgers away from the flame) and cook for another 5 minutes (exact time depends on how rare you want your burgers). If desired, during the last minute of cooking, brush your favorite BBQ sauce on top of each burger.
Coat sliced onions with olice oil and cook on grill (preferrably on a cast iron skillet) until slightly softened. Finally place open hamburger buns on the edge of grill to toast, but not burn.
Place tomato and onion slices on the bottom half of each roll. Set burgers on top of onion slices. Add dash of salt and pepper, close buns and serve with mustard and ketchup on the side.
Wine: Zinfandel or Merlot