I like Yak & Yeti. First time I tried it, I thought it was horrible - both food and service. Granted that was about 2 weeks after they opened, so I said maybe it was growing pains. I went back about a year later, and a complete turn around.I enjoy their food, and there service and kitchen pacing is a LOT better.
having said that, I have never had their sushi, and I doubt I ever will. Places that have one or two rolls on the menu are not for me. Teppan Edo is the same way. They have a California Roll and I believe a tuna roll on the menu. Ask them to make something else, and they cannot do it. Even something that has the ingredients that are in one of the other rolls. Try getting a cucumber roll - they should be able to do that, after all, its a california roll with no crab or avacado. Nope, they cant make it. Why, because all of their sushi was made hours ago in a differnt kitchen.
The fact that Yak and Yeti has one roll, and that roll is loaded with sauce, and spicy stuff tells me that the spicy tuna is most likely the scraps from trimming the tuna for their seared tuna dish, chopped up with spice, and kept in a large container in the reach in. The crab is most likely Krab. Then they load it up with sweet sauce. I'm sure it is tasty, but the taste is more about the sauce and spice than the fish.
I can't blame them, it is a great way to use any tuna scraps. However, now that I think about it, I would gather they are purchasing pre portioned tuna from their food supplier, not breaking down whole fish (or loins of fish) - so maybe their spicy tuna comes in a bag.
-dave