Matzo Ball Soup

In a large pot, bring chicken stock to a simmer. Add chicken; return the stock just to a simmer. Cover chicken with a small plate to keep it submerged, then cover the pot. Reduce heat to maintain a very low simmer; simmer until chicken is cooked through, about 1 1/2 hours. Remove chicken and let cool until easy to handle. Strain stock into a heatproof bowl. Skim off fat (reserving, if desired, to use as schmaltz in the matzo balls); return stock to the pot.

Meanwhile, in a large bowl, combine matzo meal, salt, garlic, baking powder and baking soda; set aside. In a medium bowl, whisk the 2 whole eggs with the 3 yolks, the schmaltz and the 1/4 cup finely chopped onion; set aside. In a separate bowl, whisk the 3 egg whites (or beat with a mixer) until stiff peaks form. Stir schmaltz mixture into the dry ingredients, then stir in one-third of the beaten egg whites until incorporated. Gently fold in remaining whites until no streaks remain. Press a sheet of plastic wrap directly onto the surface of the batter and refrigerate for 20 minutes or overnight, until firm.

Line a sheet pan with plastic wrap. Scoop walnut-size mounds of batter onto the baking sheet. Roll each scoop into a ball, handling them as gently as possible. (This is a bit messy; using wet or oiled hands helps.)

Return the soup to a simmer. Add carrot, celery, the diced onion, rutabaga, dill and parsley; season to taste with salt and pepper. (If you started with Andrew's recipe for unsalted chicken stock, you'll need to season more generously.) Add matzo balls using a slotted spoon. Cover and cook over medium heat, turning the balls a few times, until plump and cooked through, about 25 minutes. Meanwhile, shred chicken meat; discard skin and bones. Gently stir in chicken and cook just until the chicken is warmed through, about 2 minutes. Remove herb sprigs. Season again with salt and pepper. Serve immediately.