In a large mixing bowl, combine the cut chicken pieces with 2 tbsp low-sodium soy sauce, 1 tbsp cornstarch, grated ginger, minced garlic, and black pepper. Toss well to coat. Cover and refrigerate for at least 30 minutes, or up to 2 hours.

While the chicken marinates, whisk together pineapple juice, chicken broth, light brown sugar, rice vinegar, 1 tbsp low-sodium soy sauce, ketchup, and sriracha (if using) in a small bowl. Set aside.

Heat 2 tbsp vegetable oil in a large skillet or wok over medium-high heat. Add the marinated chicken in a single layer, ensuring not to overcrowd the pan. Cook for 3-4 minutes per side, until golden brown and cooked through. You may need to cook in batches. Remove cooked chicken from the pan and set aside.

If needed, add another teaspoon of oil to the skillet. Add the diced red bell pepper and sauté for 2-3 minutes until slightly tender-crisp.

Pour the prepared pineapple sauce mixture into the skillet with the bell peppers. Bring to a simmer, stirring constantly.

Once simmering, stir in the cornstarch slurry (2 tbsp cornstarch dissolved in 2 tbsp cold water). Continue to cook, stirring frequently, for 1-2 minutes until the sauce has thickened to your desired consistency.

Return the cooked chicken to the skillet. Add the drained pineapple chunks. Toss everything gently to coat the chicken and pineapple in the sticky sauce. Cook for another 1-2 minutes to heat through.

Remove from heat. Garnish with sliced green onions and toasted sesame seeds, if desired. Serve immediately over steamed white or brown rice.