In a mixing bowl, whisk together dark soy sauce, chicken broth, rice vinegar, light brown sugar, sesame oil, sriracha, water, and black pepper until combined.

Take the boneless chicken thighs, sprinkle cornstarch over the chicken, and add a splash of soy sauce. Toss to coat and marinate for about 10 minutes.

Heat a tablespoon of oil in a large skillet or wok over medium-high heat, add the marinated chicken thighs, and cook for about 3 minutes on each side.

In the same skillet, reduce heat to medium, add minced garlic and ginger, and sauté for about 1 minute until fragrant.

Return the cooked chicken to the skillet, add chopped red bell pepper and green onions, pour the sauce over everything, and toss well.

Simmer for an additional 3-5 minutes until the sauce thickens, then serve hot over rice with extra green onions.