Steak bombs

Ingredients

• 2 tbsp olive oil
• 1 red bell pepper, thinly sliced
• 1 yellow bell pepper, thinly sliced
• 1 large onion (or equivalent of smaller onions), thinly sliced
• Salt and pepper, to taste
• 1 lb shaved steak
• 4 slices provolone cheese (or 1 cup shredded mozzarella)
• 4 sub rolls, cut to open