Andrew Tarlow's Diner is a neighborhood institution and pioneer of gratuity-free establishments in Brooklyn. This place serves up breakfast, lunch and dinner in an old converted dining car under the Williamsburg bridge. A seasonal menu of fresh, New American style food that changes daily.
This is a pro tip, but also a summer tip, take the ferry from Lower Manhattan to Rockaway and spent the day. The beach is great and the area is impossible to gasp that it's 30 min from Manhattan (without traffic) - Eat as many tacos you can, cause it's the best in the state of New York!