STEP 1 HAND FORM & SEASON: In a large mixing bowl, combine 1 pound ground sirloin with 1/4 cup grated Spanish onion, 1 1/2 teaspoons Worcestershire sauce, and 1/4 teaspoon kosher or sea salt. With clean hands, mix gently until the ingredients are well combined. (Hand working helps the burger stay together.) Pack a 1/2-cup measuring cup with beef. Remove and mold into a slightly flattened patty about 1 inch thick. Place the burgers on a platter and grind 1/8 teaspoon pepper over them. Flip them and grind another 1/8 teaspoon pepper on top.
STEP 2 START YOUR GRILL: A charcoal or gas grill by far gives you the best flavor, but you can also use a grill pan. Whatever method you're using, always start with a clean grill.
For charcoal or hardwood: Ignite the coal or wood, and bring the coals to an even red flame. For a gas grill, heat grill to a high heat and rub grate with a folded-up paper towel dipped in olive oil (use tongs to hold the paper towel). Reduce the flame to medium. Never char your burger--it can create harmful carcinogens.
STEP 3 COOK THE BURGERS: Place burgers on grill; cook 5 minutes. Flip burgers, cover the grill, and continue cooking for another 4-5 minutes for medium doneness. (Make sure internal temperature reaches 160°.) Don't press the burger down with a spatula, or you'll squeeze the flavorful juices out (and risk creating the aforementioned carcinogens). For cheeseburgers, now is the time to top the burger with a slice of reduced-fat cheese such as Swiss, Muenster, or Cheddar. Using tongs or a heatproof spatula, transfer burgers to a clean plate or platter.
STEP 4 DRESS 'EM UP: While burgers are cooking (or before you start), put a condiment plate together. When you go with low-fat meat, you need to up the flavor in other ways. Try add-ons like thinly sliced onions, sliced ripe tomatoes, and fresh romaine lettuce leaves, all of which add extra nutrients, too. And don't forget the ketchup, Dijon mustard, relish, and sliced dill pickles. When burgers are cooked, place on the bottom half of each of 4 whole-wheat hamburger buns. Dress up your burger, cover with the top half of the bun, and enjoy.