Haw berries (shanzha; 山楂), or hawthorn berries, are near and dear to the heart of every Beijinger. So lusciously red, they ripen just in time for winter, adding the perfect dash of color to busy streets and gray, sunless skies. There’s no better way to preserve their tart, bright flavor than a thick haw berry jam, with a few kumquats for color and contrast. Ruby red, citrus-y, sweet, and tangy, it goes beautifully well with bread or sourdough english muffins, or in a linzer tart.