The strange thing about hamburgers is that few people really think about them, though they are arguably the most consumed single item on earth. (let's leave India and China out of that equation) And they are probably the most ill-treated food as far as care in preparation is concerned. So let's give it some consideration.
Opinions about hamburgers are like *noses*, everybody has one. The general consensus, though, is that the patty should be crusty on the outside and rosy on the inside. It should be made from freshly ground beef, not ground scraps, with a fat content of about 15-20%. Use enough salt, beef needs more salt than you think.
The best way to get that crusty outside is on a very hot surface, like a cast-iron frying pan. Just sear it on the outside, and then finish cooking in the oven at 190° (a toaster oven will do) To prevent it from ballooning while cooking, make a dimple with your thumb in the centre. You could squash it down with a spatula, but then you lose all the juice. The bun to meat ratio by volume should be 1.5:1, and the bun should be light and fresh with a crackly thin crust. Toasting it will do that for you.
Anything else you put in there, like lettuce, pickles or tomato, should be fresh crisp and tasty.
Here's my version: It seems like a lot of trouble, but the result is not your Mickey D's mystery burger.
For each burger:
Enough freshly ground beef (for good flavour use 50% skirt steak and 50% top round, you may have to add some fat) to make a patty 2.5 cm thick that fits the bun.
One fresh hamburger bun made from brioche dough (or whatever kind you like) cut in half.
2 Iceberg lettuce leaves.
1 large slice of tomato (1 cm), or enough smaller one to cover the bun.
Ketchup, mayonnaise or mustard to taste.
Salt & pepper.
1 slice of your preferred cheese (0.25 cm), optional.
Get your cooking surface very, very hot. Season the beef, mold the patty into a flat round without handling it too much, and make a dimple in the top with your thumb. Oil the griddle. Sear until you have a crunchy crust, flip, do the other side. If you are using cheese, drape it over the top, place the patty in a toaster oven at 190° for 3 minutes, this should bring it to medium rare. Experience will tell you when it is the way you like it. In the meantime toast the bun halves, spread with your condiment(s) of choice. Place the lettuce, pickle and tomato on the lower half, salt & pepper, top with the meat, the other bun half and that is it.