Always Homemade
Never buy pre-made burgers. Maybe some butcher burgers will be fresh and as good as you make them, but the only way to guarantee the flavour is to make them yourself.
No Salt Before Cooking
In my opinion it is best not to add salt to the seasoning of the burger mince. If you want to season the meat, use a salt free rub or simply pepper. Sprinkle salt liberally on the burger while cooking instead. This stops the meat drying out and it also ensures that every bite has an even amount of saltiness.
Use 20% Fat Mince (80% Lean)
A burger needs a good amount of fat and if you are cooking it on the grill it is going to lose a lot to the flames. Use at most 80% lean mince and if you are really stuck add some butter or oil to the burger mix to increase the fat content.
Use Brisket and Chuck
Unless you own your own mincer it might be hard to control the meat you use, but the best combination is mostly brisket with some chuck. Maybe about 80/20. Of course, the 80/20 lean to fat rule above is even more important. If you need more fat or more flavour you can also add a little pork mince.
6oz Rules
You want a burger that will take a little time to cook so as it will absorb the smoke flavours and get a nice caramelised bark. A 6oz or 170g burger is about perfect in my opinion. Make it a little wider than your intended bun as it will shrink when cooking.
Use The Indirect Method
Place the charcoal on one side of your barbeque and leave the other side free. This way you can place the burgers over the side with no charcoal and when you close the lid the burgers will cook gentle like in an oven. You can then finish the burgers over the flames.
Keep it Neat
It is ok to have a stacked burger when it is being served on a plate in a restaurant, but when you are eating around a BBQ with a beer in one hand and the burger in the other you want something a little smaller. If you want to show off then use flavours and amazing meat instead of 27 layers of random meats and vegetables. Let people have a second burger rather than making it a double - it is a much better experience.
It's All About the Toppings...
Tomatoes add umami and juiciness, but they need to be exceptionally good tomatoes. Forget the boring salad tomato and get a nice firm heritage variety.
Lettuce tastes of nothing much, but it has a purpose - it creates a barrier between the bread and the fillings which keeps the bread from getting mushy. A crispy variety can also add some nice texture and it really goes well with mayo.
Bacon is a burger classic of course, but make sure you get it crispy and that the fat is well cooked.
Pickles are essential in my opinion. The vinegar cuts through the cheese and beef fat and really brings some enlightenment to a good burger.
Which bring us to cheese. The star of the show in some ways, it brings loads of flavour, it adds contrast to the burger bark, and it makes a burger feel filling and satisfying.
Onions can serve so many roles on a burger. Raw they can take the place of pickles and cut through the stodge. Cooked fast they add some bite and loads of flavour. Cooked slow for a long time they add an intense sweetness. Tabacco onions add crunch and can bring extra salt to the party.
Last but not least is the sauce. It is the making of a good burger and should be drizzled all over the meat and allowed to flow down the sides of the sandwich. You can really control the overall flavour of the burger with your sauce choices. Try brown sauce for tang and a sharpness, tomato sauce for sweet and umami, bbq sauce for intense sweetness, and a mustard or hot sauce for a little extra bite. Of course, don't forget about mayo!
... and the Bread
A plain old-fashioned burger bun is heard to beat and all you have to do is decide with or without the sesame seeds. Always toast your bun.
Brioche is also a popular choice with a softer cake like texture and a lovely shiny crust. Just be aware that brioche can absorb a lot of grease and become very messy.
A Belfast bap is one of the kings of buns in Ireland. It is a crusty but fluffy artisan bun that gives a lot of holding power for messier or bigger burgers. When you bite into it the harder outer crust it sometimes causes the contents to squish out the far side, but the texture is amazing.
A Waterford blaa is soft on the inside and out and has a nice floury crust. I think it goes really well with a softer burger like a lamb burger and the flavour does not get in the way of more delicate fillings.
You can also use bagels, batch loaf, soda farls, crusty rolls, and many more options for your burger bun.
Cook to Temp
Buy a Thermapen instant read thermometer and use it. Burgers should be cooked fully unless you made them yourself and are very confident in the meat. Around 55c is medium rare, 60c is medium, 65c is medium well, and 70c or over is well done.
Bonus Tip
Try black pudding on your next burger. It is epic!