I like Punjabi Tandoor, too. It isn't a buffet, but they have steam trays with about 6 curries ready to go, the naan is good, and it is pretty inexpensive - about 6-7 bucks for a combo plate.
For buffet in Mira Mesa I really like Annapurna - more southern Indian, if I remember right. Even though the restaurant is small, they have a pretty good selection of curries, a few soups, and aren't afraid to make some spicy dishes. Their lamb is great. If you are on a schedule I will warn - they don't open til 11:30, and sometimes the food isn't quite ready yet when they open. Usually at Indian buffets I find the service to be slow, at Annapurna I have always had the best service.
10606 Camino, Ruiz San Diego, CA
Punjabi Tandoor is closer to I-15 than Indian Tandoor, which is almost at the west end of Mira Mesa Blvd. Punjabi's naan can be really fresh and hot, especially at lunch time...but hang tough with the wait. The chicken tikki masala and the chicken mandhi are delicious as well as the spinach dish we got along with it (i can't remember the name of it now). Get your stuff to go, small place. Maybe some folks grumble about the grumpy service...it doesn't bother me.
...and I know Ariana Kabob House isn't Indian (It's Afghani food), I can't stop recommending it because I just think the quality of the food is wonderful and they don't gouge the customer with high prices. $6.95 for lunch, that includes a generous entree, rice (depending what you order) salad, slice of bread and quick service. IMO, the lamb kabobs are pretty decent. When you exit Mira Mesa Blvd., go east, make a u-turn at the light and the place is on the right hand side next to a Denny's. Very close to I-15. Good luck Chef!
9235 Activity Rd, San Diego, CA
Ariana Kabob House
9910 Mira Mesa Blvd Ste A, San Diego, CA 92131