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