Years ago, my mom made some "copycat" White Castle burgers. I seem to recall it involved a jar of veal baby food. Urp!
I do love the real White Castles though. Sometimes you just have to have what you crave. :)
2 lb Lean Ground Beef
1/4 c Dry Minced Onion
1/4 c Hot Water
3 oz Jar Strained Beef Baby Food
2/3 c Clear Beef Broth
1 pk Hot Dog Buns
Soak 1/4 cup dry minced onions in 1/4 cup hot water until soft while you mix 2 pounds ground beef with 3 ounce jar of strained beef baby food and 2/3 cup clear beef broth.
Keep patties uniform using 1/4 cup meat mixture for each patty, flattened to 1/4" and fried quickly in 1 T oil per patty on a hot griddle. Make 3 or 4 holes in patties while frying.
Cut hot dog buns in half. Cut off rounded ends. Fry 1 t onions under each patty as you turn to fry 2nd side.
Slip each patty into bun with 2 dill pickle chips, mustard and catsup.
IIRC the "secret" to White Castle is the onions in the ground beef, very thin patties, and the meat is steamed/cooked covered rather than fried or grilled. I'll also add you get a more tender burger with higher fat content meat, such as a regular ground beef or ground chuck. Ground round or other 85 plus percent lean will be too dry and not deliver that greasy burger lol