I love Dong A for some stuff but wouldn't trust produce/meats from there if they aren't pre packaged and frozen. Too often I see things for sale in there wayyy past their expiration date. I wouldn't want to eat raw fish that might be treated the same as their other products.
If you're looking for asian marts though there's Dong A and another one across 50 from Viet Garden. I don't know its name but it makes REALLY good custard buns. Their seafood seems pretty fresh. They had blue crab still alive sitting in crates one day while I was there and their fish seemed like it came in that day(ish).
You could also try the Whole Foods Market there is one on Sand Lake and one near Winter Park, too. The one on Sand Lake i've been to is HUGE and they promote organic and fresh foods. They have a large selection of fish that looked good so that may be an option. They also have dry aged beef yum!
I was wondering if you are into salmon? I've recently found a desire to move to the Seattle area and in doing so have been educating myself about salmon. Apparently many people are saying to go with wild caught. It is a healthier fish than the farmed because of what the farmed fish are fed and with strong population control is better for the environment due to the pollution farming salmon can create.
I <3 Sushi. My favorite place so far has been Amura but to eat local since I'm over in avalon park there is a place called Wasabi Sushi thats on the east colonial side of Avalon Park (and conveniently next to cold stone ice cream) and their rolls have been excellent.
I think if I were in the PNW with popular and clean asian groceries with fresh catches of the day I'd indulge in learning how to make sushi for now but I have to admit I like using it as an excuse to get out of cooking and to get out of the house
Best of luck with your endeavors, I love to cook but have been really focusing on being efficient for making meals for 2 and unfortunately hubby doesn't eat sushi. Now if anyone wants to talk grilling I'll throw down anytime
