1. To make the marmalade: In large nonaluminum casserole, heat the oil over medium-high heat. Add the onions and sauté for 10 to 15 minutes, or until well softened.

2. Add the red wine, port, and sugar. Reduce heat to low and simmer until almost all of the liquid has evaporated, about 15 minutes. Add the water and cook to reduce the mixture until it is thickened. (The onions should be very tender and slightly caramelized.) Add the thyme, salt, and pepper. Remove from heat. Taste and adjust the seasonings and set aside.

3. Remove the meat from the refrigerator 30 minutes before grilling. Liberally season the steaks on both sides with seasoning salt. Prepare a barbecue grill or an oiled grill pan for medium-high-heat grilling. Grill the steaks for 7 to 9 minutes on each side for medium-rare. Turn them so that you get criss-cross marks on the steaks. (The steaks should be almost charred on the outside. An instant-read thermometer inserted in the center of a medium-rare steak should register 135°F.)

4. Place on a carving board and let rest for 10 minutes. Cut the steaks against the grain into ½-inch-thick slices and serve immediately, with the warm onion marmalade.

Advance Preparation:

The marmalade may be made 3 days ahead, covered, and refrigerated. Reheat gently just before serving. Add more water if the mixture is too thick.

The clever cook could:

1. Serve the marmalade on crostini with a sprinkle of crumbled goat cheese on top.

2. Use the marmalade as a condiment for grilled chicken or sausages.

3. Use the marmalade on other cuts of beef as well, such as flank steak, triangle tip, or Porterhouse.