Actually it's the only Sri Lankan anywhere in Manhattan, as far as I know. Which might make it one of a handful, at most, in the country?
Anyway, it's called Taprobane. My friend brought me there for my birthday. She's been several times over the past few years. The food was great, service warm. The place was completely unassuming amidst Times Square and office buildings. The decor is not high end, so it's not for power meals. The food was very unusual for me- a mix of Indian (mulligatawney soup, etc) and Carribbean in the sense of foreign influences- roti (whose origin I do not know) and even sausage rolls! Many spicy dishes. Curries and rice dishes in banana leaf. I have their flyer on me- it says they have parking validation available, too.
They seem slow, though my friend says the experience was the same as years ago. I really felt bad. I cannot attest to the place's authenticity since I only discovered the cuisine by visiting the restaurant. But it was very good food.
And check out their website (link below).
Taprobane Sri Lankan Restaurant
234 W 56 St (between Broadway and 8th)
MANHATTAN, NY 10019