Funny thing is that I just got back today from 10 days in San Diego.
Bubble teas and Chinese food @ 99ranch.
Go to Sam Woo BBQ at 7330 Clairemont Mesa Blvd #103. It is the place in the back of 99 Ranch Market (market is bulk of building, other side has a few stores), with the hanging roasted ducks. That place has the BEST boba milk tea. They have various flavors, but their original boba milk tea is the best. That place also has pretty tasty and cheap Chinese takeout. For take out I always custom order the beef tendon dish. It isn't in their normal takeout selection.
Rubio's is always good. They are Baja style fresh Mex specializing in battered fish tacos and burritos. It's a regional chain that started in San Diego, and they have restaurants here and there.
If you like Pho, my favorite place is called Pho Hua on 4717 El Cajon Blvd. I always get their #1 bowl and a Thai tea, and squirt liberal amounts of Sriracha sauce into the bowl.
There's an Asian take out place on 6935 Linda Vista Rd (I think) that specializes in dim sum style dishes. Not the best dim sum in the world, but still tasty and really cheap. It is attached to the Thuan Phat supermarket.
If you want really good dim sum, try Emerald Seafood Restaurant. It is on 3709 Convoy Street.
For an Asian buffet, try the Super Buffet (whatever it is called, name has changed several times) at 8998 Miramar Road. Very tasty of course, and very extensive. They often have stuff like crab legs. I've even seen frog legs there! They have sushi and sashimi, as well as Mongolian BBQ.
If you want an adventure, head East on Interstate 8 for 2 hours until you get to El Centro, and eat at Celia's Restaurant on 1530 Adams Avenue. Get the special quesadilla. It is a raw tortilla filled with queso and deep fried until it puffs up golden and crispy. Supposedly these deep fried quesadillas are a local invention. Their chips are really good and unique, and their salsa is really spicy. I always get their chorizo tostada - my favorite chorizo in the world. Their tacos are also good.