Heat 1 Tbsp. oil in a large deep-bottomed skillet over medium-high heat. Season chicken with salt and pepper, then add to skillet. Saute for about 5 minutes, flipping occasionally, until the chicken is cooked through and no longer pink on the inside. Remove chicken and set aside.

Add an additional 1 Tbsp. oil to the skillet, then add in the onion, peppers, carrots. Saute for about 5 minutes, stirring occasionally. Add garlic and cook for another 3 minutes or until the vegetables are tender yet still a bit crisp. Remove vegetables and set aside.

Add ketchup, sriracha, vinegar, brown sugar, oyster sauce and white pepper to pan, and whisk to combine. In a separate bowl, whisk together the fruit juice and cornstarch until it has dissolved. Then add the mixture to the sauce. Bring to a boil, then reduce heat to medium-low. Add back in the vegetables and chicken, and the pineapple, then stir until evenly coated.

Remove from heat and serve over rice, garnished with sesame seeds if desired. Serve immediately, or refrigerate in a covered container for up to 3 days.