Well, the temperature is expected to top 80 degrees on Wednesday, with partly cloudy skies and a caressing breeze: not a bad birthday present for our nation, which will be turning 236 years old. What better way to celebrate than with that pastoral American tradition: a picnic. We asked a few of our city’s most talented chefs to offer a culinary prescription for a successful and portable Fourth of July meal. Bring these baskets down to your local park, garden or recently rezoned waterfront esplanade and enjoy a patriotic chow-down. We’ll kick things off with Marcus Samuelsson, the chef and owner of the soul-food mecca Red Rooster Harlem...