Never mind what goes on the burger, what should go in the burger is minced garlic and hot pepper and maybe a little Worcestershire sauce.
Purist answer: Not even that.
Not-Quite-So-Pure: A little garlic, a little pepper, maybe a 70/30 mix of ground round and hot Italian sausage, pretty much whatever floats your boat.
I was going to suggest Thousand Island, although mayo, ketchup, and relish in the right proportions can add up to a passable substitute.
Quick guide to proper condiment usage:
Hot dogs get mustard.
French fries get ketchup.
Hamburgers get Thousand Island.
Most other sandwiches get mayo.
The first person to say it’s all a matter of personal taste gets slapped with a trout.
At the risk of being labeled a communist and un-Australian, I’ve never been a fan of pineapple on a burger. I love pineapple, just not on a burger.
However double yes to the Beetroot, Bacon and Fried Egg. Hell if you’re truly desperate you can do without the bacon & fried egg, but without beetroot whatever it is you’re eating is not a burger. It may possibly be food, it may even be edible, but it ain’t a burger without the beetroot.
I came in to suggest the same thing, but it’s right there in the OP.
Turkey burgers, smoked fontina and avocado for your burgers?I want to come to your house!
And if you go with the bacon suggestion, even better!
Right. Altho Malt Vinegar can sub for ketchup on fries.
C’mon you so called English speakers, get it right! They are called “beets” not “beetroot”.
Beetroot this, Beetroot that…you guys are driving me crazy.
Are the beets that go on an Aussie burger pickled sweet and sour (Harvard), or plain?
I’ll third Worcestershire Sauce. That stuff is GOOD. Campion, you should try at least one burger that you douse in Worcestershire before grilling. I have never tasted a bad burger that had this stuff applied pre-cooking.
I’ve been limited to drinking Sprite and water for the past couple of days (can’t keep anything else down). Damn you, damn you, damn you. AND my husband brought back a load of mesquite from his farm.
Oh, and anyone who thinks s/he doesn’t like dark chocolate probably hasn’t had the GOOD dark chocolate. I used to think I only liked milk chocolate, and then I tasted the good stuff. I haven’t looked back since.
A small suggestion, if I may: how about a selection of several kinds of mustard? There’s the ballpark yellow stuff, grey poupon, stone-ground, horseradish mustard, and several others. Offer these on the side to your family.
Love, Phil
That’s OK, it’s only promoting Fascism if you leave the pineapple off. 
So very, very true. Then again, I feel the same way with regards to bacon on my burgers- Anything without bacon OR beetroot on it is not a burger, IMHO. The sooner other countries realise this, the better. 
Yes, besides adding taste it also adds a nice tiny bit of crispy texture too.
No worries. I specifically warned the OP against this particular atrocity long before those crazies had a chance to post. Actually, beetroot is very toxic. The first sign of trouble, is that they like beetroot. Once that happens they are done for. Pretty soon they are putting beetroot on pizza. It’s best to put them out of their misery or send them to some kind of penal colony.
beer, as in cook with. You WILL be holding one as you cook them :dubious:
Makes a good tenderizer.
I was wondering about the beet thing too, and whether they’re pickled. Just before my last cookout, my wife pulled up the lone surviving beet in our garden, so I sliced it really thin and stuck it in the fridge in a bowl of white vinegar, and then I let folks put it on their burger if they liked. It was pretty good, sort of like sweet cucumber pickle chips, but I preferred eating the pickled beet and the hamburger separately: the beef overpowered the beet.
Daniel
Mayonnaise, mustard, olive oil or butter on a hamburger bun will help seal the bread against moisture — helpful if you’re the kind who puts on garden-fresh lettuce sparkling with dewdrops like in the burger commercials.
Salsa
Dude! That would have been awesome, but I didn’t think of it.
I turned the grilling over to my BIL, and deferred to him on spicing/seasoning the burgers before cooking them. He said nothing but salt and pepper, and I didn’t hear any complaints from the hungry folk. I did forget to put out the onion, but only because I was busy gabbing with my mom instead of focusing on food prep.
Thanks for all the suggestions, particularly those who suggested hamburger buns. 
My six year-old little girl came up with the following hamburger:
"Daddy, can I have a hamburger? I want the spicy cheese (pepperjack) on it!
Oh, and… (thinks for a moment, then her eyes lit up)
Daddy, can we put pepperoni on it??? PLEEEEAAASSSEEE???".
So I seared some pepperoni slices (4 per burger) until they were crispy, cooked a couple of burgers, melted some pepperjack cheese on them, and had one of the best burgers I’ve ever eaten.
If Sophie grows up cooking food like that, she’s going to make some man very happy.
Pico de gallo. That’s chopped tomato, onion, cilantro, jalepeno & lime juice for you who have never had it.
FWIW,
Rob