Mix soy sauce, garlic, hot pepper sauce, and ginger together in a large bowl until well combined. Add chicken to the bowl, turn to coat evenly, then cover and marinate in the refrigerator for at least 1 hour.

When ready to cook, remove chicken from the marinade and shake off excess. Reserve marinade in the bowl.

Heat sesame oil in a Dutch oven over medium-high heat. Add brown sugar and stir until dissolved. Add onion and sauté for 5 minutes. Add chicken; cook and stir until evenly browned, about 5 minutes. Add water and reserved marinade and bring to a boil.

Reduce the heat to low and simmer for 15 to 20 minutes. Add peanut butter, stir until well combined, and simmer for 10 more minutes. Transfer chicken to a serving platter, pour the sauce over top, and garnish with green onions.