How would I go about recreating beef/hamburger taste/umami, strictly vegan? I've begun to experiment with creating the perfect vegan hamburger. Hamburgers was something I held very dear before I stopped eating meat and I haven't been able to find something that even comes close to a meat based burger.

Now I've done some experiments with seitan and I feel that I'm getting there with the texture and chewiness, however the taste is still far off and I would like to ask you for your best tips on recreating the beefy taste that hamburgers have. 

I've tried the usual, soy, ketchup (or dried tomatoes), garlic, onions, marmite, nutritional yeast and vegan worcestershire sauce. And of course a tad of liquid smoke, but I feel lost and unable to track down what I miss and need to make it just right.
Cooks Illustrated has an ultimate veggie burger recipe that you can adapt. Their key to umami is cremini mushrooms.  I've made that recipe and it was well received. Of course, no one mistook them for real hamburgers, but the patties tasted quite good. 


MSG (monosodium glutamate) is to umami flavour what sugar is to sweet flavour. So if you're pro-msg, you can try that, too.  And pleanty reasons not to ;)
I recommend trying shitake mushrooms as well.
Also try up to 5% wheat germ/flour which should help with the caramelization and related flavours. 
grated vidalia onions in the patties also help (caramelization and umami).