If you for some insane reason already haven't, make your way up to the Essex Street Market.
The grocery vendors have a strong variety of produce, herbs, canned goods, snacks and everything else you need on a weekly basis. Further inside, you'll come across butchers and the such to get some of the best meats and fish in town.
The Essex Market is also home to the Brooklyn Taco stand for a quick lunch and Davidovich Bagels all day for your bagels and lox needs. Porto Rico has amazing coffee for $1.25 and way in the back you can grab an ice cream cone to embrace the approaching summer.
Check out the full list of vendors here.