When you are hunting around Boston for something ethnic, where do you head? For me, (and I live in Arlington), I aim for these places..
I am not listing meat, seafood, and produce, but there are enough threads here mentioning Dewars, Russos, Savenors, etc.
Korean/Japanese - Reliable Market or Kotobukiya (till May 10), H-mart when it finally opens..
Chinese - Super 88 (I like the one in Malden) or Ming's Supermarket
Middle-Eastern - Arax and Sevan in Watertown
Italian - Salumeria Italiano in the NE or Bob's Food in Medford
Mexican/South American - Hi-Lo in JP, Tropical Food on Washington
Eastern European - Berezka Deli or Bazaar in Allston
Spices - Penzeys in Arlington or Christina's in Inman
As for Indian, seems like there are small markets everywhere, but there's a place in Waltham on Moody that seems well stocked..