Heat the Oil: In a large skillet over medium-high heat, add the olive oil.
Cook the Chicken: Add the sliced chicken and cook for 5-7 minutes, until golden brown and fully cooked. Remove and set aside.
Sauté Aromatics: In the same skillet, add the chopped onion and cook until softened (about 2 minutes). Stir in the minced garlic and cook for another 30 seconds.
Add the Sauce: Stir in the pineapple chunks, soy sauce, honey, rice vinegar, and red pepper flakes. Let it simmer for 2 minutes.
Combine Everything: Return the cooked chicken to the pan, toss to coat, and let it simmer for 5 more minutes until the sauce thickens.
Serve: Remove from heat and serve hot over rice, quinoa, or vegetables.