Since Ratner’s scion Theo Peck introduced borscht to his Myrtle Avenue shop, Peck’s, last April, the chilled golden-beet soup, infused with a shot of Gefilteria’s tangy kvass, has become a menu staple. Every cool slurp offers a balance of sweet and sour, enhanced by a pile-on of complementary garnishes, including shreds of green cabbage and a warming horseradish crème fraîche. In this soup, as in others, Peck shows an understanding of produce developed during time spent in the kitchen at Blue Hill at Stone Barns. See, too, daily specials like gazpacho, and a vegan raw zucchini and cucumber soup. In the winter, you’ll be carrying home his confit chicken and matzoh ball soup by the pint.