Every wonder about the difference between ground chuck and ground sirloin? Ground chuck contains about 20% fat, a sure thing when juicy burgers are in order. But we wanted a leaner burger, so we chose ground sirloin with just 10% fat. But don't worry, we packed in extra flavor with the addition of bacon. Shredded cheddar covers the burgers evenly but adds up to less cheese than a full slice. The flavorful patties get topped with grilled onions, spinach, and a spicy special sauce. We made ours with heart-healthy olive-oil mayo, ketchup, and sriracha. Cutting the sweet ketchup in half means you'll skip some of the added sugar then if you used ketchup alone.
