In a large 4-to-5-quart pot, combine the boneless skinless chicken thighs, minced garlic, grated ginger, chopped scallion whites, kosher salt, and freshly ground pepper. Pour in enough water to cover the ingredients, about 6 cups. Bring to a rolling boil over medium-high heat.

Once boiling, reduce heat to low, and simmer uncovered for approximately 15 minutes.

While the chicken simmers, whisk together the black rice vinegar, soy sauce, and toasted sesame oil in a small bowl. Add chili oil to taste if desired.

After 15 minutes, carefully remove the chicken from the pot using tongs and place on a cutting board. Shred into bite-sized pieces.

Add the dried ramen noodles and matchstick carrots to the pot, stirring well. Cook according to package instructions, typically 3-4 minutes, until the noodles are tender.

Once the noodles are cooked, stir in the shredded chicken to heat through.

Taste the soup to adjust seasoning with additional salt or pepper if desired. Ladle into bowls, topping each with fresh scallion greens, and drizzle with the mixed sauce.