Preheat an electric griddle according to manufacturer's instructions or a stovetop griddle over medium-high heat; lightly grease surface.

Place mushrooms, onion, and bell pepper on half of griddle; place roast beef on other half. Cook and stir each half separately, chopping beef into smaller pieces, and seasoning with salt and seasoned salt.

Place provolone cheese over beef when vegetables tender and beef is hot until melted. Turn off griddle. Divide cheesy beef among rolls; top with mushroom mixture.