Preheat your oven to 425°F. Line a baking sheet with parchment paper.
Thinly slice the red bell pepper, zucchini, and red onion. Toss the vegetables with a light spray of cooking oil, salt, and pepper, then spread them evenly on the baking sheet.
Roast the vegetables in the oven for about 20-25 minutes, stirring halfway through, until tender and slightly charred.
Meanwhile, prepare the chicken by lightly pounding the 4-ounce chicken breast to ensure even thickness.
In a shallow bowl, mix the whole wheat flour with a pinch of salt and pepper. In a separate bowl, whisk the egg white until frothy.
Dip the chicken breast first into the flour, shaking off any excess, then into the egg white, and back into the flour to create a thin, crispy coating.
Heat a non-stick skillet over medium-high heat and lightly spray with cooking oil. Place the coated chicken breast in the skillet and cook for about 4-5 minutes on each side until golden and cooked through.
In a small saucepan over medium heat, combine the pineapple chunks, low-sodium soy sauce, rice vinegar, and honey. Allow the mixture to simmer for 3-4 minutes until it slightly thickens into a sweet and sour sauce.
Plate the crispy chicken alongside the roasted vegetables, then drizzle the sweet and sour sauce over the chicken. Serve immediately and enjoy the medley of flavors.