I've been searching "Mimi"... I've been going there doggedly for years and always assumed "Mimi"!! Now, I know.
When asked for a recommendation for Vietnamese resto, I ALWAYS recommend one of two places: Pho Phuong on College and Mi Mi. Both are a little off the beaten path, but definitely worth the trip.
Mi Mi is family run and has a friendly and warm atmosphere. I recently took some friends there who were mostly vegetarian and they were super cool about adjusting dishes to make them work for everyone at the table. They have always been super accommodating.
It's a nice open space. Lit well with a nice amount of space between the tables (ie - not packed like sardines!).
Me? My usual there now is the bbq pork with egg and rice noodle (dry) with soup on the side ($7-ish). I don't think I eat it right because I always ask for the fish sauce for it and dump it onto the noodles... but their bbq pork is RIDICULOUSLY good. I've also had the rice dishes, pho and the vermicelli dishes and they are all a step above most Vietnamese places in the city.
Mi Mi: It's worth the trip to Chinatown 2.