malibu, I don't know if you have time to search old posts before your lunch today, but there have been lots of discussions of lunch in that area. For example, people who have jury duty or are staying at the Marriot hotel often ask this question. You could try searching under Brooklyn Heights, DUMBO, Montague Street, jury duty, Marriot, etc.
Just throwing out a few quick ideas:
Lantern Thai at 101 Montague - although they usually rush the meal, since most people have to return to work,
Heights Cafe - also on Montague Street , nicer atmosphere, not so rushed, food is okay or
QUEEN - great old-school Italian place on Court Street. Food much better than the above two places, although also more expensive. I think they have a $25 three-course lunch special? Try their fresh mozzarella appetizer.