Before you start: these sandwiches, and those like them, draw part of their majesty from the fact that they are overstuffed. That being said, you need strong bread and I highly recommend having wax paper and aluminum foil ready to go (aluminum at the minimum, if you don't have wax paper). Wrapping these sandwiches helps the bread squeeze all that goodness in and not break apart. If you do not have wrapping materials, you can still make these sandwiches. You will simply need to consider larger rolls, or breaking 2 sandwiches into 4 - using 4 rolls instead of 2. If you have a flat top grill or griddle, fire that up over medium-high heat. Otherwise, heat a large, wide skillet or pan over medium-high heat. If using a pan or skillet, you may want to make one sandwich at a time.
Slice your bread in half, lengthwise, making sure not to cut all the way through. Keep both halves together.
2-4 6-7 Inch Hero or Hoagie Rolls
Optional: spread a thin layer of mayo on the inside of the bread.
Mayo
Open the bread and toast it, inside down, on the griddle or pan. Give it a minute or two until it reaches your desired level of color.
Set the bread aside and add the ground beef to the pan (1/2 for each sandwich, if you are cooking in batches). Using a spatula, break it apart and spread it across the cooking surface. You want as much beef to cooking surface as possible.
1 Lb Ground Beef
Let the beef cook for 2-3 minutes, crisping up at the edges and getting some nice color. As it cooks, give it a light sprinkling of your seasonings (I like salt, pepper and garlic powder - the O.G. is rumored to have used seasoned salt).
Salt and Pepper to Taste
Add in the chopped onion (again, 1/2 for each sandwich) and stir to mix. Let the meat and onion sit and fry in the pan another 2-3 minutes. Give it another light sprinkling of your seasoning.
1 Medium Onion
While the meat and onions cook, spread mayo evenly over the inside of your roll. As much as you like.
Give the meat and onions another stir and split the portions up for each sandwich (1 portion if you are cooking in batches, or 2 portions if cooking for both sandwiches at once).
Bunch each portion into a rough shape of your bread, and top each portion with 2 or 3 slices of cheese (I like 2 slices per 1/2 lb of beef). Cook another minute to let the cheese melt.
4-6 3/4 Oz. Slices American Cheese
Chop the cheese and meat together using your spatula. When the cheese is broken up, mix the meat and cheese until the cheese it melted throughout.
Give it one last check for seasoning and then scoop the meat/cheese mixture onto one side of your bread (let any excess grease drip back into the pan/griddle).
Top the meat with a drizzle of ketchup, a layer of tomato slices and a layer of shredded lettuce. Close the sandwich up. I recommend wrapping it, as detailed below.
1 Large Handful Shredded Iceberg Lettuce, 1 Medium Tomato, Ketchup
Recommended step: wrap each sandwich in wax paper and then foil to get that street food style wrapped sandwich. If you don't have wax paper, foil works fine on its own. Wrapping helps mash all the flavors together and gives the bread some help holding together. Letting the sandwich sit for a few minutes to rest will also help all the flavors marry. Enjoy!