How to Make It
Peel and slice the ginger crosswise into 4 or 5 coins, then smack with the flat side of a knife. Set aside. Cut the hollow green parts of the green onion into thin rounds to yield 2 to 3 tablespoons; set aside. Cut the leftover white sections into pinkie-finger lengths, bruise, then add to the ginger.
Coarsely chop the leafy tops of the cilantro to yield 2 tablespoons; set aside. Reserve the remaining cilantro sprigs.
Add the coriander seeds and clove to a 3- or 4-quart pot over medium; toast 1 to 2 minutes or until fragrant. Add the ginger and green onion mixture; stir 30 seconds or until aromatic. Slide the pot off the heat and cool for about 15 seconds, then pour in the stock. Return the pot to the heat; add 2 cups water, cilantro sprigs, and chicken. Bring to a boil over high. Lower the heat, and gently simmer for 30 minutes. While the broth simmers, soak the rice noodles in hot water until pliable and opaque. Drain, rinse, and set aside.
After 5 to 10 minutes of simmering, the chicken should be firm and cooked through (it should yield slightly when pressed). Transfer the chicken to a bowl, flush with cold water to stop the cooking, then drain. Cool and cut or shred into bite-size pieces. Cover loosely to prevent drying.
When the broth is done, pour it through a fine-mesh strainer positioned over a 2-quart pot (line the strainer with muslin for a super-clear broth). Discard the solids. You should have about 4 cups broth. Add fish sauce and sugar or maple syrup, if needed, to create a strong savory-sweet note.
Bring the strained broth to a boil over high. Put the noodles in a noodle strainer or mesh sieve and dunk into the hot broth to heat and soften, 5 to 60 seconds. Lift the noodles from the pot and divide between 2 large bowls. Lower the heat to keep the broth hot while you arrange the chicken on top of the noodles and garnish with the chopped green onion, cilantro, and a sprinkling of pepper. Return the broth to a boil before ladling into the bowls. Enjoy with basil, mint, sprouts, chile, and lime, if desired.