Vegetarian French Dip Sandwiches

Ingredients

• 1 yellow onion
• 3 portobello mushroom caps
• 2 Tbsp butter
• Pinch of salt and pepper
• 1/4 tsp dried thyme
• 1/4 tsp dried oregano
• 2 cups vegetable broth
• 1 Tbsp soy sauce
• 1/2 Tbsp brown sugar
• 1/8 tsp garlic powder
• 4 6-inch French or Ciabatta rolls
• 4 slices provolone

Directions

1. Cut the onion into thin strips. Rinse the portobello caps so any dirt is gone, then cut each cap in half and slice crosswise into 1/4-inch thick pieces.
2. Put the butter in a deep skillet and add the sliced onions. Cook over medium heat for a few minutes, until the onions are just starting to soften. Add the sliced mushrooms, a pinch of salt and pepper, the thyme, and the oregano. Continue cooking until the mushrooms have given off their moisture and the pan looks dry again, about 10 minutes. You should see some browned juices clinging to the bottom of the skillet, but keep them from burning.
3. When those cooked-down juices start sticking to the skillet, add the vegetable broth. Scrape and stir so the browned bits loosen into the liquid. Stir in the soy sauce, brown sugar, and garlic powder. Bring the liquid to a simmer, then reduce the heat to low and let it simmer for about 5 minutes while the bread toasts.
4. Split the rolls and set them on a baking sheet with the cut sides facing up. Set the oven to broil and slide in the pan. Stay close, and broil until the edges are only lightly browned, about 5 minutes.
5. With a slotted spoon or tongs, lift the mushrooms and onions from the au jus. Portion the mushrooms and onions onto the 4 rolls, then lay a slice of provolone on each sandwich. Put the sandwiches back under the broiler for a few minutes more, just until the cheese melts. Close the sandwiches and serve them with the au jus from the skillet for dipping.