Preheat your oven to 425°F and line a baking sheet with parchment paper.
Slice the Chicken Breast into bite-sized strips, pat dry, and season lightly with salt and pepper if desired.
In a bowl, whisk together the egg white. In another shallow dish, combine panko breadcrumbs and cornstarch.
Dip each chicken piece first in the egg white, then coat evenly in the breadcrumb mixture.
Place the coated chicken pieces on the baking sheet. Bake for 15-18 minutes, turning halfway, until the chicken is cooked through and the coating is crisp.
While the chicken bakes, prepare the sweet and sour sauce. In a small saucepan, combine pineapple juice, rice vinegar, tamari sauce, and honey. Warm over low heat until the mixture is slightly thickened, about 3-4 minutes.
In a skillet, lightly toss the red bell pepper slices and pineapple chunks for 2 minutes until just softened.
Once the chicken is done, transfer it to a serving bowl. Drizzle the warm sweet and sour sauce over the chicken and garnish with the sautéed bell pepper and pineapple.
Serve immediately and enjoy your crispy baked sweet and sour chicken.