If you have a meat grinder... Buy short rib meat or chuck steak and grind it yourself. If not buy it and have the butcher grind it for you. Tell the butcher you want a coarse grind on the meat. Not the small grind they use to make regular hamburger.
You want your ground beef to be between 20 to 30% fat content. You will get 2 burgers per pound. For 2 burgers, before you form your burgers mix in... 1/4 teaspoon of black pepper, 1/4 teaspoon of garlic powder, not garlic salt, add a 1/4 teaspoon of onion powder. Do not use any salt yet.