Now here's the next trick: Instead of making the usual six burgers, make 12 very thin burgers. Put a decent square of feta cheese in the middle of one burger, cover with a second one, squish the edges to make one double thickness burger, enclosing the feta. Make six double thickness feta-enclosing burgers.
Now. Burn them. AGE the surface... Glycate those amino acids over glowing charcoal.

Two is more than enough, for me anyway. I don't care how good they taste, I manage two and have pigged out. I guess polishing off the left over feta during preparation may have something to do with this!
We have a plan to add shredded tarragon or fennel leaves to the next batch. Salt, pepper AND a herb. Livin' dangerously here.
Sorry for no chance to reply to emails or comments. Too busy barbecuing after a heavy weekend on call.
Peter