Wash your hands.
Place burger in frying pan if you wish to do this inside, or the grill if you want to do it outside. (Note that a nice side effect of doing this in a pan is that the drippings season the mushrooms nicely. YMMV.) If the meat is in a pan, coat the pan with olive oil first, and/or use a nonstick pan, unless you want to be scraping beef off the pan for approximately ever. Sear the meat on medium-high or thereabouts; this means cook it until it is nice and dark, preventing the juicy goodness from the core of the burger from escaping. Flip it and sear the other side. As you're doing this, put the ginger seasoning on the outside of the burger, and salt and pepper it to taste. (I've had good experiences with the ginger, but then I like strange tastes. YMMV, again.) Once both sides are fairly well-seared, cook it on medium-low until the inside is done to taste. (The point at which you have to stop searing is a matter of personal discretion and experience.) Once the burger is done, keep it in a warm place for a moment while the mushrooms are being cooked. (The mushrooms can be cooked simultaneously if the burger is on the grill, but they will not be as flavorful.)
Wash your hands.
Put some olive oil and butter in the pan, about half-and-half. (Use all butter if you so desire; I use olive oil to cut it because it's a bit lighter and the result isn't quite as goddamned greasy.) Set burners to "high", let the butter melt. Use a lot of oil; we're sauteeing. Add as much garlic as you want; I budgeted a half tablespoon, but I use a lot more than that when I cook 'em. Previously, you should have sliced the mushrooms into "wafers" of anywhere from 1/8" to 1/4" (depending on your dexterity); now throw 'em in the pan. Stir them constantly, and add more grease as needed to keep them loose in the pan. If you're using white mushrooms, they'll darken, and they are "done" when they are appealing to you. I like mine one shade lighter than charcoal and limp. I'll dump in a little bit of water if things are getting too hot (i.e. black stuff is beginning to form on the bottom of the pan). Add salt as desired.
Retrieve the burger from its place of warm repose, and empty the mushrooms onto the top of it. Use either the grill or the pan (after suitable wiping) to melt the cheese slice(s) onto the top of the burger and mushrooms. (This "seals" the mushrooms onto the burger; you can do it the other way, but in my experience this way is "neater" to consume. Your call.) We're almost done.
Ah, the bun. Yes, the bun is important. Onion rolls are good. So are potato rolls. French bread is quite tasty, and even wheat or whole-grain bread can be good under the right circumstances. Under _no_ circumstances use fucking whitebread or one of those nasty Wunder-rollz, this is a fucking QUALITY BURGER and any attempts to cheesedick it will earn you an eternity of sulfur-skiing on the Lake of Fire in Culinary Hell. Go ahead, test it. I dare you.
To prepare the bun, first slice it (evenly, don't make any divots or angle-slices on it, lest you want a fucking mess on your hands when you try to consume this lovely chunk of meat). Butter the faces, wipe out the pan, set burner to medium-high, wait for it to heat a bit, then place the two halves of the bun butter-side-down on the surface. You're browning the bread here. Check it every few seconds, don't let it burn or you're going to have a carbonized bun fairly quickly. When it's a nice shade of brown (shouldn't take long, maybe a minute or two), pull it off and set it aside. Slather a generous coat of the stone-ground mustard on both halves, then place the burger on one. Top with ketchup if you desire. Place a leaf of lettuce on the other half and two thick slices of tomato. Enjoy the burger, it will bring you joy.
You may add other condiments. Horseradish, relish, onions, pickles. Exercise good taste. Do not select just any fucking limp sliced cucumber corpse to sit atop this creation, get a real crisp kosher dill. Don't chop the onions (if you need more than are in the meat already), slice them, and use good purple or white onions, not that yellow stew-fodder shit. Use a decent horseradish and relish, don't go for the cheap stuff. (If you want "cheap", go to fucking Burger King instead.) Do not use mayonnaise at all, you want to taste the burger and not white axle grease.
The advantage to this recipe is that it doesn't require _too_ much in the way of implements, the clever can find a way to do it with a minimum. (If you don't want the mushrooms, then you only really need the grill.) I bring it up because a woefully small number of people seem to season their meat in any meaningful way before they consume it, preferring to just put salt and pepper on it and eat it. Mmm, scorched cow flesh. Not. It needs something to give it some kick, dammit. It's not food, it's a fucking experience.
This is not the end-all recipe, I seek more seasoning to bring it to the state of Perfection. I'm trying a bit here and there, but haven't found too much else that's agreeable to the general palate.
Source: MadHat@Unspecific.com, Wednesday 2003-04-02