Cut the chicken thighs into bite-sized pieces and season lightly with salt and pepper.
Combine soy sauce, sesame oil, garlic, ginger, and brown sugar in a bowl. Add chicken pieces and marinate for about 10 minutes.
Rinse the jasmine rice under cold water until it runs clear. In a saucepan, bring 2 cups of water to a boil, add the rice, reduce heat, cover, and simmer for about 15 minutes.
In a large pot, heat a tablespoon of oil. Add the marinated chicken pieces and sauté until caramelised and cooked through, about 5–7 minutes.
Pour in the chicken broth and rice vinegar, bring to a boil, then reduce heat to simmer.
Slowly add the cornstarch mixture while stirring continuously to thicken the broth. Simmer for an additional five minutes.
Taste and adjust seasoning with salt or pepper if desired.
Serve the chicken over fluffy jasmine rice.
Garnish with sliced green onions before serving.