Ethnic casual dinner between Newport and Laguna
Wow-- that's a pretty teensy window. You're basically limiting yourself to Corona del Mar and Newport Coast.
That said, it's a zone very light on the places you're seeking. High-income ZIP codes don't attract alot of indie ethnic joints.
My pick for ethnic would be Bamboo Bistro-- Thai-Viet type fusion
2600 E Coast Hwy, CdM
If you're serious about finer dining, there's Mastro's, Javier's and Sage at Crystal Cove Promendae (Newport Coast). And in CdM on PCH, Oysters, Bandera, The Bungalow. I would avoid Landmark ... but Crow Bar Kitchen is a fave-- but noisy when busy.