4 1-inch-thick slices of Vidalia onion or other sweet, large onions, plus leftover onion for grating (3-4 tablespoons)
Extra virgin olive oil (EVOO), for liberal drizzling
Salt and pepper
1 1/2 pounds ground beef (choose chuck for buttery burgers or sirloin for leaner patties)
1/4 cup Worcestershire sauce
2 tablespoons spicy mustard
4 slices good-quality Swiss cheese
4 slices good-quality white bread, toasted and lightly buttered
Heat a large cast iron skillet over medium-high heat. Secure the onion slices with toothpicks so that they stay intact when flipped. Dress the onions with EVOO, salt and pepper and add to the hot pan; caramelize the onions for 3-4 minutes on each side.
While the onion slices cook, place the meat in a bowl and mix with the Worcestershire sauce, mustard, salt, pepper and grated onion – grate the onion directly over the meat so that it catches all the juice.
Remove the onion slices from the skillet, then drizzle a little more EVOO into the pan and wipe it around with a paper towel. When the pan smokes, add the meat in four mounds; press the mounds down with a spatula and cook for 4 minutes, until brown and crisp. Flip and press again, caramelizing the second side. Fold the cheese to fit the patties, place the cheese on top of the burgers, then cover the pan with loose foil for a minute to melt the cheese. Remove the pan from the heat.
Place the patties on the buttered toast and top with the Vidalia onion bullseyes. This is one of many "Yum-o!" recipes – it's good and good for you. To find out more about Yum-o!, Rachael's nonprofit organization, go to www.yum-o.org.