In a large pot, combine chicken thighs, garlic, ginger, scallion whites, salt, and pepper. Pour in water or chicken stock and bring to a rolling boil.

Reduce heat to medium-low and simmer uncovered for about 15 minutes until chicken is cooked through.

In a medium bowl, whisk together black rice vinegar, soy sauce, and sesame oil. Add crispy chili oil if desired.

Remove chicken, shred it, and add ramen noodles and carrots to the pot. Cook noodles according to package instructions, 3-4 minutes.

Return shredded chicken to pot and stir gently, heating through for 1 more minute. Taste and adjust seasoning as needed.

Serve in bowls, topping with reserved scallion greens and seasoning mixture for extra flavor.