For onions, tear a 36x18-inch piece of heavy foil. Fold in half to make a double thickness of foil that measures 18x18 inches. Place onions in the center of the foil. Combine melted margarine, mustard, and honey. Drizzle over onions. Bring up two opposite edges of foil and seal with double fold. Then fold remaining ends to completely enclose onion mixture, leaving space for steam to build. Place packet on an uncovered grill directly over medium coals for 15 minutes.

Meanwhile, in a medium bowl combine ground beef, salt, and pepper; mix well. Shape mixture into four 3/4-inch-thick patties. Add patties to grill. Grill patties and onions for 5 minutes. Turn patties. Grill for 8 to 10 minutes more or until an instant-read thermometer inserted in side of patty registers 160 degree F. and onions are tender. To serve, toast both sides of Texas toast on grill. Top each slice of Texas toast with a lettuce leaf, a burger, a tomato slice, and one-fourth of the onions. Sprinkle with fresh ground pepper, if desired. Makes 4 servings.

Arrange preheated coals around a drip pan in a covered grill. Test for medium heat above pan. Place patties on grill over drip pan. Place onion packet directly over medium-hot coals. Cover and grill for 20 to 24 minutes or until an instant-read thermometer inserted through side of patty registers 160 degree F and onions are very tender, turning patties once halfway through grilling time.