There are few Portuguese restaurants in New York, and fewer of them are really good, but one, located just two blocks from the LIRR Jamaica Train Station is not just authentic, but the food is excellent.
I am speaking of A-Churrasqueria. This is a family-owned and operated restaurant with a warm and inviting friendliness. This restaurant layout is typical Portuguese: A long bar where food and drinks are served and is the living room to the local Portuguese community and, behind it, a dining area where the non-Portuguese speaking types sit among traditional Portuguese families.
The Bacalhau Assado (grilled salted codfish) is the best I know... The owner, and sometimes chef, upon my expression of appreciation to him about the Bacalhau Assado, described the exhausing process he goes through to make it as good as it is; part of which involves soaking it for almost four days in clean, continuously cycled ice water.
Before the meal, traditional Portuguese rolls with fine Portuguese olive oil are served.
The wine list is impressive, most of the deserts are made on premises, and some are resourced from Portuguese bakeries in Mineola or Newark, NJ. There is no real ambiance here... Its a bar with a dining room -- be governed accordingly.