Heat 2 tablespoons of olive oil in a large skillet over medium-high heat.
Add the thinly sliced chicken to the skillet and cook for 5 to 7 minutes, stirring occasionally, until completely browned and cooked through.
Add the sliced red, green, and yellow bell peppers to the skillet with the chicken. Cook for an additional 5 minutes until the peppers are tender.
Season the mixture evenly with the salt and black pepper, tossing to coat.
Divide the chicken and pepper mixture into 4 equal portions directly in the skillet. Place 2 slices of provolone cheese over each portion.
Cover the skillet for 1 to 2 minutes, or until the cheese is completely melted.
Use a large spatula to carefully transfer each cheesy portion into a sub roll.
Garnish with chopped fresh chives and serve immediately hot.