Mushroom french dip sandwiches recipe

Ingredients

• 2 tsp unsalted butter
• 2½ Tbsp olive oil, divided
• 2 large yellow onions, vertically sliced
• ¼ tsp kosher salt
• 1¼ lb portobello mushroom caps, gills removed, sliced into strips
• ¾ cup lower-sodium vegetable broth
• ⅓ cup dry sherry
• 1 Tbsp vegetarian or vegan Worcestershire sauce
• 2 tsp chopped fresh thyme
• 1 tsp lower-sodium soy sauce
• ¼ tsp black pepper
• 2 Tbsp Dijon mustard
• ½ tsp prepared horseradish
• 4 (2-oz) whole-wheat hoagie rolls, split
• 4 very thin Swiss cheese slices (such as Sargento Ultra Thin)

1. Heat butter and 1½ teaspoons oil in a large skillet over medium. Add onions; cook, stirring occasionally, 10 minutes. Reduce heat to medium-low; cook, stirring occasionally, until golden, about 30 minutes. Stir in salt; cook 5 minutes.
2. Heat 1 tablespoon oil in a separate large skillet over medium-high. Arrange half of mushrooms in skillet in a single layer and cook, undisturbed, until golden brown, about 3 minutes. Stir and cook, stirring often, until golden brown all over, about 5 minutes. Transfer mushrooms to a bowl. Repeat process with remaining 1 tablespoon oil and remaining mushrooms.
3. Return cooked mushrooms to pan. Add broth, sherry, Worcestershire, thyme, soy sauce, and pepper. Bring mixture to a boil. Reduce to a simmer; cook 5 minutes. Using tongs, remove mushrooms to a bowl. Divide the jus evenly among 4 ramekins.
4. Stir together mustard and horseradish in a bowl. Spread on top halves of rolls.
5. Preheat broiler to high. Arrange ¾ cup mushrooms on bottom half of each roll. Top each with ¼ cup onions. Tear each cheese slice in half; place two halves on each sandwich. Place sandwiches on a baking sheet; cover with top halves of rolls. Broil until cheese melts, 1 to 2 minutes. Serve with jus for dipping.