To warm rolls, arrange them on a baking sheet and place in an oven set on low. Heat oil in a large nonstick skillet over medium heat. Add onion, zucchini, peppers, 1/4 tsp. salt and Italian seasoning. Cook, stirring, until vegetables are just tender, about 5 minutes. Transfer to a bowl and keep warm.
Season steak strips with remaining 1/4 tsp. salt and freshly ground black pepper. Add to the same skillet and cook over medium-high heat, turning once, until no longer pink, about 2 minutes.
Place one open roll on each of 4 plates and top with 2 slices provolone. Add steak and vegetables, then serve.