A good place to try local Hawaiian shrimp is at the Giovanni's Shrimp Truck located in Kahuku. They have three types of shrimp plates - the classic scampi (with garlic), lemon & butter shrimp, and hot & spicy.
I always stop by when I'm in the area and I usually eat the scampi. It is really delicious. The only thing I don't like is that sometimes the food is too oily. They use regular oil and I usually eat organic and virgin oil, so their oil makes me feel a little heavy on the stomach after I eat there.