In a large bowl, combine chicken thighs, soy sauce, lemon juice, bay leaves, minced garlic, black pepper, and star anise (if using). Cover and refrigerate for at least 2 hours or overnight.

Heat 2 tablespoons of cooking oil in a large pot over medium-high heat. Add the marinated chicken thighs and cook for 4–5 minutes per side until golden brown. Remove the chicken and set aside.

In the same pot, add chopped onions and minced garlic, sautéing for about 5 minutes until the onion is soft and translucent.

Stir in the tomato sauce, reserved marinade, and oyster sauce, mixing well for 2–3 minutes until heated through.

Return the browned chicken to the pot, adding water to cover the ingredients and sugar to balance acidity. Cover and lower the heat to a simmer, cooking for about 10 minutes.

Incorporate cubed potatoes, stirring gently. Cover and continue to simmer for another 15 minutes.

During the last 10 minutes of cooking, add chopped bell peppers into the pot, stirring occasionally.

Once the chicken is tender and the vegetables cooked, serve the stew hot with steamed rice or crusty bread.