For brunch, the classic dish to get is the Feijoada, but the benny is also solid (and i don't recommend a benny lightly)—you can also ask for ham and spinach together (my favorite). For dinner you can also get the same thing, or the Moqueca (shrimp stew) is incredible. Pro-tip: if you're there for breakfast on a weekday, ask for a egg and cheese (add bacon or ham or avocado) on a croissant. Not on the menu—sounds basic, tastes amazing.
My second-favorite outdoor-place in Manhattan. The abandoned 1.6 km rail tracks running above Chelsea down to the Meatpacking district were turned into an above-ground park. Perfectly nice place for sitting in the sun, reading, relaxing, having lunch in some green spot in the city. Nice views at the Hudson River, New Jersey, the Statue of Liberty (little small from there but still visible) and the architecture around Chelsea.
The permanent piece called "Meeting" at MoMA PS1 is an etherial experience of light and color and quiet. Sit and look through the cutout in the ceiling and watch the light change both outside and in. You can't tell what you're looking at until maybe a bird flies by.