What's the most appropriate way to thaw hamburger meat?
I like to put the meat in a largish ziplock bag and flatten it out so it occupies the whole flat area of the bag but is only a couple of cm think.  Then I press a chopstick into the meat lengthways both horizontally and vertically to create indents in the meat, as if I was making a naughts and crosses (tic-tac-toe) grid.

Then I freeze it lay flat in the freezer.  Then when I want to use it I can 'snap' off squares of meat (along the indentation lines) to the amount that I need and I don't need to defrost the whole pack in a single go.

To defrost (I don't have a microwave) I leave the pieces on a metal tray for a little while, turning occasionally.  This usually defrosts them in an hour or so, depending on how many there are