Vegetarian Mushroom Philly Cheese Steak Sandwiches

Details

Ingredients

• 1 tablespoon butter, divided
• 1 tablespoon olive oil, divided
• 1 (8 ounce) package baby bella (cremini) mushrooms, sliced
• ½ teaspoon fresh thyme leaves
• salt and freshly ground black pepper to taste
• 1 tablespoon soy sauce
• 1 bell pepper, sliced into strips
• 1 onion, sliced
• 2 slices provolone cheese, cut in half
• 2 hoagie rolls, split lengthwise
• 2 teaspoons Dijon mustard, or more to taste