Umami Burger

So...  I was in LA this week and I had a free night on my hands.  I went on line and looked up "The Best Burger in LA".  I came up with Umami Burger.   Of course I've heard the word Umami before but was not sure what it was.  Called the 5th taste,  it still didn't make any sense to me.   So here it is right from their website--

What exactly is umami?Taking its name from Japanese, umami is a pleasant savoury taste imparted by glutamate, a type of amino acid, and ribonucleotides, including inosinate and guanylate, which occur naturally in many foods including meat, fish, vegetables and dairy products. As the taste of umami itself is subtle and blends well with other tastes to expand and round out flavors, most people don’t recognize umami when they encounter it, but it plays an important role making food taste delicious.

I realized that one of their locations was only 3 miles from my hotel.  I pulled out the GPS and jumped in the car.  Unfortunately the place was packed on a Thursday night.  I was hoping to get a spot at the bar but there were only 4 bar seats and all were taken.  I waited for about 15 minutes and after seeing no movement, I ordered my burger to go.  I got the Umami burger and sweet potato fries.   Once the burger was ready, I headed back to the hotel. 
So, I should have asked what was on the Umami burger.  It was topped with grilled onions, grilled tomatoes and mushrooms.  They were big mushroom that I think were Shitake but I'm not sure.  The thing is, I have a real dislike for slimy food.  I can't stand mushrooms when they are slimy.  I pulled those off the burger and chowed down.  Overall it was a pretty good burger.  They do a small version of the cheese skirt (not nearly as big as the Squeeze Inn cheese skirt.)  The meat was pretty tasty and the sauce was a sweeter version on ketcup.  The bun held together well.   I would give it an 8 on the burger scale.  But, the fries rocked!  The sweet potato fries were sprinkled with brown sugar or Cinnamon or a combination of both.  They were to die for.  I ate every single one and almost licked the paper.  The fries get a big 10.  
Next time maybe I can actually sit in the restaurant and eat!