In a medium bowl, whisk together the soy sauce, ketchup, brown sugar, chicken broth, pineapple juice, ginger, garlic, rice vinegar, and sesame oil until well combined.
Place the chicken breasts in a large resealable plastic bag or a shallow dish. Pour the marinade over the chicken, ensuring it is well coated. Seal the bag or cover the dish and refrigerate for at least 2 hours, preferably overnight.
Preheat your oven to 375°F (190°C).
Remove the chicken from the marinade, reserving the marinade for later use.
Place the chicken breasts in a baking dish and bake in the preheated oven for 25-30 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (74°C).
While the chicken is baking, pour the reserved marinade into a small saucepan. Bring it to a boil over medium-high heat, then reduce the heat and simmer for about 5 minutes, or until slightly thickened.
Once the chicken is done, brush it with the thickened marinade before serving.
Variations & Tips
For a spicier version, add a teaspoon of sriracha or a pinch of red pepper flakes to the marinade. If you prefer using chicken thighs, they can be substituted for the breasts; just adjust the cooking time as needed. For a smoky flavor, try adding a teaspoon of liquid smoke to the marinade. If you have access to a grill, consider grilling the chicken instead of baking for an authentic taste.