Make the Meatballs:

1. In a large bowl combine the chicken, panko, minced garlic, soy sauce, grated ginger, half the scallions, 1 tablespoon fish sauce, lemon grass, cilantro and 2 tablespoons of broth. Use your hands or a rubber spatula to gently mix, just until combined. Use your hands to scoop out about a tablespoon and form mixture into (1’’-diameter) meatballs. Transfer to a plate or clean work surface lined with parchment paper. Repeat until all meatballs are formed.
2. In a medium pot over medium heat, combine remaining broth, water, Thai chili, smashed garlic, shallot, sliced ginger, 1 tablespoon fish sauce and remaining scallions. Bring to a gentle simmer over medium-high heat. Reduce heat to maintain a simmer and cook for 15 minutes. Use a slotted spoon to remove solids and discard. In a small bowl combine miso with 2 tablespoons of the broth and whisk to combine. Add the miso mixture to the pot of broth. Stir to combine.

Meanwhile

1. Heat oil in a large skillet over medium heat until shimmering. Add meatballs to skillet (in batches if necessary to not overcrowd the pan) and cook, turning occasionally, until golden brown on all sides, about 6-8 minutes. Remove and transfer to a clean plate.
2. Add the bok choy and crushed red pepper flakes to the broth. Simmer until bok choy is almost tender, about 3 minutes.
3. Add in the meatballs and bring broth back to a simmer. Simmer until meatballs are cooked through, about 5-8 minutes. Taste broth and adjust for seasoning with salt and pepper.
4. Serve garnished with scallions and crushed red pepper flakes.