In a large mixing bowl, whisk together the pineapple juice, soy sauce, honey, garlic, ginger, rice vinegar, and olive oil until fully blended. If you’re using whey protein powder to boost protein content, add it at this stage and whisk thoroughly to prevent clumping. The marinade should be slightly sweet, tangy, and aromatic — like tropical sunshine in a bowl!

Place chicken breasts in a resealable bag or shallow dish, pour the marinade over, and seal. Refrigerate for at least 2 hours — or overnight if you want deeper flavor. The acidity from pineapple juice helps tenderize the meat, while the soy and honey infuse it with a delicious savory-sweet balance. Turn the chicken halfway through marinating for even coating.

Preheat your grill or grill pan to medium-high heat. Lightly oil the grates to prevent sticking. Remove chicken from marinade (save ½ cup of it for later). Grill each side for about 6–8 minutes, depending on thickness, until internal temperature reaches 165°F (75°C). You should see nice golden-brown grill marks and caramelized edges.

While the chicken grills, pour the reserved marinade into a small saucepan. Whisk in a cornstarch slurry (1 tsp cornstarch mixed with 1 tbsp cold water). Bring to a gentle simmer over medium heat and stir until it thickens into a glossy glaze — about 3–4 minutes. This will be your finishing sauce, rich and shiny like restaurant-style teriyaki.

In the last minute of grilling, brush a generous layer of your homemade teriyaki glaze over each chicken breast. This locks in moisture and adds that beautiful sticky-sweet finish. Let the chicken rest for 5 minutes before slicing to retain all its juices. Serve with rice, roasted veggies, or grilled pineapple for the full Hawaiian experience.