Step 1

Meatballs : Mix scallions, egg, egg yolk, ginger, garlic, soy sauce, coriander, salt, and pepper in a large bowl. Finely grate zest from lime into bowl. Add chicken and gently mix with your hands until evenly distributed.

Step 2

Gently roll chicken mixture into 1½"-diameter balls (about the size of a golf ball; you should have about 20) and place on a baking sheet. Chill until ready to use.

Step 3

Do Ahead: Meatballs can be formed 2 months ahead; freeze until firm, about 2 hours, then transfer to a resealable plastic freezer bag and keep frozen.

Step 4

Broth and Assembly : Heat oil in a large saucepan over medium. Add ginger, garlic, and pepper and cook, stirring often, until garlic is golden brown, about 4 minutes. Add 6 cups cold water, increase heat to medium-high, and bring to a simmer.

Step 5

Working with 1 meatball at a time, reroll to ensure it’s round and gently add to broth. Reduce heat to medium-low and add soy sauce; season with salt. Cook meatballs until cooked through, 10–12 minutes. Add celery and snow peas and cook until peas are bright green and tender, about 3 minutes.

Step 6

Divide soup among bowls. Top with scallions and cilantro.