Pat the shrimp dry with paper towels and season lightly with black pepper.
Heat olive oil in a large skillet or wok over medium-high heat. Add the shrimp and cook until pink and opaque, then remove from the pan and set aside.
In the same pan, add a little more oil if needed and sauté the garlic until fragrant.
Add the sliced bell peppers and onion, then stir-fry until they are tender but still slightly crisp.
In a small bowl, mix soy sauce, honey, oyster sauce, cornstarch, and water until smooth.
Pour the sauce into the skillet and stir continuously until it thickens.
Return the shrimp to the pan and toss everything together until well coated. Cook for another minute to combine flavors.
Sprinkle with green onions and red pepper flakes if desired, then serve immediately.