Summarize this article in one sentence.
Cast-iron skillets are recommended for the best results, but you can use any frying pan you have. If you are using a cast-iron pan, you can speed up the heating process by placing it into a preheated 350° F (176° C) oven for about 20 minutes and removing it with an oven mitt. Starting with a piping hot cast-iron pan is key. Add a small amount of cooking oil to the pan. Don't use more than 1 tablespoon (0.5 ounces). If your oil smokes, your pan is a little too hot. Take it off the burner for a couple minutes and try again. When the beads of oil spread evenly and shine, the pan is ready for cooking! Place your patty in the middle of the pan and let it cook. Your burger patty will sizzle once it hits the pan and it might even smoke. This is good. Cook it for about 4 minutes. Resist the urge to poke and prod at your patty. Don't push it down into the pan. Leaving your patty alone will allow for it to form a delicious thick crust that will seal in the flavor. Once and only once, when you see the underside starting to turn brown, flip your burger. Cook for an additional 4 minutes on the other side.  The last few minutes of cooking is the perfect time to add a slice of cheese. Place a slice of cheese onto your patty and let it get perfectly melted in the last minute or so of cooking. Your burger is medium-rare at an internal temperature of 130 to 135° F (55 to 57° C). Your burger is medium at an internal temperature of 135 to 150° F (57 to 65° C). Your burger is medium well at an internal temperature of 150 to 165° F (65 to 74° C). Your burger is well done at an internal temperature of 165° F (74° C) or greater.

Summary:
Preheat your skillet. Test the heat of your pan. Grill your burger. Flip your burger.