This is my go-to burger recipe now. I use 93% - 96% lean ground beef, but the burgers are very moist and flavorful, due to the sauteed onion/ketchup mixture, and small amount of oil for the saute (I use olive oil, for a healthier choice.) I don't make the extra sauce, but these burgers are a giant hit with everyone EVERY TIME. My 10-year-old niece and nephew BEG me to make these, any time we visit! I hope your family will enjoy this recipe as much as mine does.