Heat the vegetable oil in a large skillet or wok over medium-high heat.
Add the diced ham and cook until it starts to brown, about 3-4 minutes.
Add the garlic, red bell pepper, and green bell pepper. Stir-fry for another 2-3 minutes until the peppers are slightly softened.
Add the pineapple chunks and cook for another 2 minutes, allowing them to caramelize slightly.
Add the cooked rice to the skillet, breaking up any clumps with a spatula.
Pour in the soy sauce, oyster sauce, and sesame oil. Stir everything together until the rice is evenly coated and heated through.
Add the sliced green onions and stir to combine.
Season with salt and pepper to taste, then serve hot.

Variations & Tips
For a vegetarian version, you can skip the ham and add more vegetables like peas or carrots. If you prefer a spicier kick, add a chopped chili or a dash of hot sauce. For a more protein-rich dish, consider adding scrambled eggs or cooked shrimp. You can also experiment with different types of rice, like brown rice or cauliflower rice, for a healthier twist.