Preheat cast iron skillet or griddle on high – you want it as hot as you can get it.
Form the beef into a loose meatball. Season with salt.
Place vegetable oil into the hot skillet or griddle. The amount of oil you need will vary based on the type of skillet or griddle you’re using. It’s better to use less oil than more for these burgers since you want to make sure there’s good contact between the meat and the skillet.
Add meat into the hot cast iron skillet or griddle.
Smash immediately, and only smash once. Don’t smash again! If you do, the burger won’t be juicy.
Flip at about 2-3 minutes. You’ll know it's time to flip because you'll see the outer edges of the patty are starting to turn brown and bubbles will form. When you flip, the bottom should be dark brown.
Cook for another 3-5 minutes until the burger is done to your liking.
If you’re making a cheeseburger, add the cheese while the burger is still on the skillet and melt the cheese. This is also a great time to toast the bun.
Remove burger (and bun) from skillet and assembly with your favorite toppings.
Serve and eat immediately