In my quest for authentic, spicy, thai food I went to Asia Grocery (1010 W Cavalcade St Houston, TX 77009; around the corner from the airline dr mexican market), recommended by the owner of a thai restaurant in rice village. Not only a grocery store, but it also has authentic thai food prepared in the back (and upon request).
it looks like a run-down 7-11 with bars over the doors but if you cook thai food, and eat thai food, this market is good. fresh galangal, ginger, chilis, kaffir lime leaves, mint, thai basil, (2 other fresh greens i didn't recognize) frozen krachai, pink dried shrimp, roasted chili flakes, 1lb of mung bean sprouts for $1, fresh noodles! 3 types of freshly prepared roasted chili paste (roasted red chilis and garlic with some sugar), a jalapeno roasted chili paste, and a third, lighter red one). in the back is a kitchen where i requested sticky rice and papaya salad, spicy, made on the spot ($5). One of the cooks was placing at least 3 lbs of fish in a huge pot for fish stew. I sampled a vegetarian stew of mushrooms, bamboo shoots, greens, and sweet potato (spicy!) perhaps prepared for the two monks who came in when I was checking out. freshly made mini bean cakes with yellow bean paste, not too sweet, and flaky pastry. I will be back!
(having recently moved here i've been having some difficulties finding northern thai/lao food. although the owner of this market recommended thai gourmet on richmond. anyone been?)