If you go to the North Shore, the shrimp trucks are a huge draw but we LOVED Kono's. It's a small place with some picnic tables, but they have these things called pork bombers that are out of this world. Almost two years later, and I still dream about it! They have breakfast as well. Highly recommend lunch at Kono's and then a stop up the street at Matsumoto's for shave ice. If you're looking for something nicer or maybe dinner later on, Haleiwa Beach House is beautiful.
If you venture to Kailua, I believe there is a Kono's there as well.