Sushi / grass-fed steak in Burlington VT?
I rarely order a steak or burger when eating out and if your desire is to eat grass-fed or finished beef, you would be best served to hit Healthy Living and grill/sear/braise it at home. Sushi is very subjective and so dependent on the chef so I would try Asiana House and San Sai (I think Sakura on Church St. is closed).
There's yummy sushi to be had at Sushido in Williston. It's in the same shopping center (Taft Corners) as the 99 Steak house, but on the other side of the mall. It looks something like a hole in the wall, but it has the best sushi I've had in the area, though I admit I haven't tried a lot elsewhere. Another place that might have good Sushi is the place just up the road from there. I can't remember what it's called, but it's on the right, just next to the road that goes to the farm supply store, you go past Taft Corners mall and just before the next light there's an Asian place. They've got good Thai and Chinese food, and I've not tried their sushi but I like their Thai and Chinese. :)
I don't know if you mean a good steak cooked in a restaurant or for home. In the past there really haven't been great places to get a really good restaurant grass-fed steak anywhere in the area. That might have changed in recent times, but I'm not pulling any particular spots out of my head. Hopefully someone else will know.
If you want to purchase your own grass-fed ground beef or steaks, you can buy North Hollow Farms meats at pretty much every food coop (there's one in Burlington... is that City Market?). They also sell their beef to consumers directly through their website. I bought a side of beef from 'em a few years ago. 8 cubic feet of meat in the freezer, but only $3 a pound for the whole side (which was around 250 lbs hanging weight), and they brought it to my husband's office because he was close enough to the Hunger Mountain Coop in Montpelier where they deliver meat every week. Nice thing about North Hollow is they're a big enough operation that you can specify which cuts you want, and how much ground you want from them. I got a tongue that I still haven't cooked because I'm expecting it to take all day and I haven't set aside a day for it yet.
There are a fair number of farms in the state that sell a wide variety of meats that are locally raised and responsibly farmed. Bought a lamb this winter from a guy I know. :)