Preheat the oven to 475°F (246°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 and brown on both sides, about 4–6 minutes total depending on thickness.
Add the sliced red bell pepper, green bell pepper, and thinly sliced sweet onion to the skillet with the chicken and continue cooking, stirring occasionally, until the vegetables are tender and the chicken is cooked through, about 6–8 more minutes.
Place the split rolls open-side up on a baking sheet. Divide the cooked chicken and pepper-onion mixture evenly among the rolls.
Top each sandwich with one slice of provolone. Place the baking sheet in the preheated oven and heat until the cheese is melted, about 2–4 minutes.
Remove from the oven and close the sandwiches. Serve immediately.