In heated skillet Sautee sliced onion until soft and lightly caramelized. Remove onions from skillet and set aside.
In same hot skillet, break frozen steaks into small pieces and cook over medium heat. While cooking, turn and stir until steak pieces are evenly browned. Remove from skillet and drain to remove excess drippings.
Divide pizza dough into 4 equal parts.
Roll out one section of pizza dough on cutting board or other flat work surface, form into circle.
On one half of the pizza dough circle, place a generous amount of cooked steak and onions.
Sprinkle meat mixture with shredded mozzarella cheese.
Fold dough over in half so edges meet. Pinch and roll edge slightly to seal dough around half circle.
Using kitchen shears, cut a few small steam vents in the top of the Stromboli.