Brew the ginseng tea by mixing together the boiling water and red ginseng packets until dissolved. Set aside.
Place 2 garlic cloves, 1 date, 1 piece of ginseng if using, 1 chestnut if using and 2 tablespoons of rice into the cavity of each bird. Skewer each closed with a toothpick. Place the remaining rice in a double-layer piece of muslin or cheesecloth with the remaining ginseng and date. Tie the cloth closed tightly but leave a little bit of extra space for the rice to expand. Place the chickens and rice bag into a large, wide heavy-bottomed pot. Cover with the tea, and top off with water to cover, if necessary. Bring to a boil over high heat. Reduce the heat and simmer, occasionally skimming away any fat that comes to the surface, until cooked through, about 2 hours. When done the chickens should be very soft and fall apart easily when tugged at.
Carefully transfer the chickens to 2 bowls and divide the broth between them. Top the chickens with chile threads and garnish with pea shoots and a sprinkle of black sesame seeds. Drizzle with the sesame oil. Unwrap the rice package in a separate bowl and sprinkle with black sesame seeds, if you like. Serve with salt and pepper on the side.
You can use fresh ginseng in this soup--it is much cheaper and more readily available than steamed and aged dried red ginseng. Find and save the wishbone when eating this soup and make your soup extra magical by making a wish!