I’m a big fan of Fish House Vera Cruz, which is actually in San Marcos – just a bit east of Vista on Hwy 78. Large variety of mesquite-grilled fresh fish from a daily menu. Don’t miss the Potatoes Romano as one of your sides. They also have a fish market in-house. There used to be outposts in Carlsbad and Temecula, but now it’s down to the mother ship. It’s my favorite restaurant in the San Diego area, and when I’m headed to SD via Hwy 15, I always stop there – it’s worth the brief detour.
URBN coal fired pizza in Vista
Pure Project just opened up a tasting room in Vista. Great beers and food trucks. One of the best breweries in all of SD.
Richard Blais new restaurant at The Aviara is getting good reviews but I’ve never been.
If you are driving back up to LA after your visit to San Diego, consider stopping at Kawamata Seafood in Laguna Nigel / Dana Point.
Heading north on I-5, take the Camino De Estrella exit, and hang a left (west towards the coast) and the place will be on your right.
Why stop here? Because they have the best Hawai’ian style Poke this side of the Pacific (none of that pedestrian Costco or Bristol Farms junk). And their seaweed salad ain’t half bad either. Get there early because if they run out, they run out. You’ve been warned.
To continue along @ipsedixit’s recommendations if you’re driving back up from SD, also in very South O.C. area is Heritage BBQ. It is the finest Texas-style BBQ in L.A. / O.C. by a wide margin! Totally worth a stop.