Cook the chicken: Heat oil in a skillet over medium-high heat. Cook chicken for 2-3 minutes per side until golden, then set aside.
Saute onion and garlic: Add onion and garlic to the skillet and cook until softened, about 3-5 minutes.
Add seasonings: Pour in soy sauce, vinegar, and season with garlic powder, pepper, and bay leaf.
Simmer chicken: Return chicken to the skillet, bring to a boil, then reduce heat to medium-low. Cover and simmer for 35-40 minutes until the chicken is cooked through.