Mushroom French Dip | Umami

Ingredients

• 3 tablespoons extra-virgin olive oil, divided
• 1 medium onion, thinly sliced
• 2 cloves garlic, thinly sliced
• 4 large portobello mushroom caps, gills removed, cut into 1/4-inch-thick slices
• 12 ounces oyster or shiitake mushrooms, trimmed and coarsely chopped
• 1 tablespoon Dijon mustard
• 1 tablespoon chopped fresh thyme
• 1 ½ cups reduced-sodium vegetable broth or mushroom broth
• ¼ cup dry sherry
• 4 small whole-wheat hoagie rolls, halved lengthwise
• 4 slices provolone cheese