Shape meat into 3 portions, then work them a LOT and form into a frisbee shape, with an upward, concave bend and slightly more meat around the edge. It would take ages to overwork your meat, so don't worry about that. Working the burger makes the patty hold together, and when you're not using a binding agent, that's important. The saucer shape allows the meat to expand and will make a nice, flat shape in the end.
Start heating a cast iron pan to medium high.
Just before you put the patties in your pan, liberally salt them with a full even layer of salt. This is important for building a nice crust on the outside of the burger. But make sure it's RIGHT before you put them in the pan, otherwise you'll draw out the moisture.
Add beef or bacon fat to the pan and cook the patties flat side first. Don't move it or press it. When the sides turn a medium brown, flip. If grilling onion, before you flip it you can put a slice on the raw side and press it into the meat a little, then flip and let the onion and patty cook together.
Add a slice of cheese, then check doneness by comparing the feel of poking the burger to poking the flesh of your palm, just below your thumb. When same, plate it.