Mitasie Vegan Cafe in Lake Forest. They only have this location and their original location in HB (their HB location is a full service sit down restaurant unlike their LF location).
I also liked Huntington Ramen in Fullerton and Tama Sushi in HB, but I haven't been to them in a while.
Gracias Madre in Newport Beach. It’s vegan but don’t let that deter you, the food is great. But that helps you avoid the egg and seafood allergy. And they even have notes on the menu for items that are “nut free” so you should be covered
dinner menu
This is going to sound a bit odd, but King's Donuts in MV for pupusas and plátanos fritos con crema y frijoles. Their donuts are v good also, but I alllllways go for the pupusas.
Nice Burger MV is also pretty good vegan, as well as Mitasie (LF is the one I go to.)
For more upscale Italian, try Oliver's Osteria (the drive to the restaurant is also fun, there's lots of hiking trails along the way and an art college that's spread out). If you want regular diner/American food Nick's is good. There's also Urth cafe if you want a vegan option.
For some beachside…
C'est Si Bon for the French Pastries. It's off Riverside and PCH. I usually go to the Sbux nearby and haven't yet had a chance to stop in because I'm always busy. They don't offer WiFi, though. I've heard from several NB residents that it's amazing. (I just moved here.)
Cafe Gratitude off of…
Like it’s been said Buena Park is a little better for Korean food. Han Yang is pretty well known in these parts. Their galbi tang is quite good, right next door to Kaju Tofu.