Mark's is a little dive restaurant near Lihue which has amazing plate lunches. I can't remember the exact location but maybe someone else knows.
I was in Kaui for my brother's wedding this past October and Mark's catered the Friday night rehersal dinner. His wife, a native Hawaiian, grew up eating at Mark's and its my brother's favorite restaurant on the island.
It was probably the best meal we had all week, hands down!
Poke, @ Ara's Sakana-ya in Hanamaulu. They make it fresh several times a day. I just like Ara's recipe.
Hamura's for Saimin, it's a Kauai landmark. It may be crowded around lunch and dinner time...and if it is raining.
Local breakfast favorites...Tip Top Restaurant in Lihue, Dani's in Lihue.
I live here...this is where I go.