Preheat the oven to 475°F (245°C).
Season the chicken strips with kosher or sea salt, black pepper, and dried oregano (if using).
Heat 1 tablespoon canola oil in a large skillet over medium-high heat.
Add the seasoned chicken to the hot skillet and cook until browned on both sides and cooked through, about 6–8 minutes depending on thickness.
Add the sliced red and green bell peppers and the thinly sliced sweet onion to the skillet with the chicken and continue cooking, stirring occasionally, until the vegetables are tender, about 5–7 minutes.
Split the rolls open and place them cut-side up on a baking sheet.
Divide the cooked chicken, peppers, and onions evenly among the open rolls, then top each with a slice of provolone cheese.
Bake the assembled sandwiches in the preheated oven until the cheese is melted, about 2–4 minutes; watch carefully to avoid burning.
