Quite simply: Not a good burger.
Forgive me, but I think if you're going to call yourself Gourmet Burger Co, your mainstay burger should be passable.
I honestly don't remember the last time I had a 'tough' burger before today. Lots of little hard bits. Just not quality beef. The bun is sort of dry and the tomatoes are green.
Staff was nice and salad was good (thankfully), but definitely not a repeat performance.