Manti are dumplings/ravioli stuffed with minced beef in a yogurt sauce.
I don't think i've seen it anywhere around town. Or for that matter many Turkish restaurants either.
Some of the Armenian groceries on Washington in Pasadena have frozen manti--it's pretty good and easy to prepare. I've never seen manti in a restaurant though.
Try calling avo's in Reseda,serra's in studio city, sako mediterranean in reseda and there's a place i can't remember in huntington beach that has turkish food.
Moonlight Sako's Mediterranean
6736 Corbin Avenue
Reseda, CA 91335
The turkish student associatin at Caltech's website says that cravings on sunset is a turkish restaurant, so give them a call as well. Perhaps they can help you.
Manti are also Central Asian. Uzbekistan has them, although I didn't like them (or it) very much.
Is the traditional Turkish way to serve Manti is with the tomato sauce and the garlic yogurt dip?