Whether you like your burgers well done but have difficulty keeping them juicy... only have access to 90/10 lean beef instead of the optimal 80/20... or just want to add a little extra flavor while turning your burger into a chin-dripping gusher, here's a quick trick that'll ensure your hamburgers are the juiciest on the block.
When you forming your patties, stick a little pat of butter in the middle:
Seal the patty back up and finish forming it (flatten out a little):
Then season with a bit of salt and grill. As you can see in this example, for the purpose of demonstration I even pushed the boundries to the limit - taking this bundle of beefy joy past well done to the point of char...
...and yet, as you can see, thanks to that little pat of butter that was stashed inside it, even though the outside is crispy the inside is still glistening with juice:
Oh, and remember our little secret for tender burgers: When you're forming you patties, work the hamburger as little as possible - just enough to for the patty to hold together. If you look at the last picture closely, you can still see the 'strings' of beef that were formed when the sirloin came out of the grinder.
By working the burger as little as possible and ensuring those grinder strings are still fairly intact in your finished patty - e.g. not squeezing, mashing, and compressing your ground beef into a solid mass of mush - you'll ensure each sumptuous bite is as tender as can be.
Other than that, just keep an eye on your cook times and you'll be good to go.
Ligth 'em up and enjoy those burgers my fellow grilling addicts!