French Dip Sliders Recipe

Ingredients

• 1 tbsp olive oil
• 1 tbsp unsalted butter
• 2 tbsp water
• 1 large onion, thinly sliced
• salt
• pepper
• 12 Hawaiian slider rolls or buns, see notes 1
• 3 tbsp mayonnaise
• 1 tbsp Worcestershire sauce
• 1/2 tbsp horseradish
• 1/2 tbsp Dijon mustard
• 1/2 tsp garlic powder
• 1/2 tsp onion powder
• 12 slices provolone, divided
• 1 lb deli roast beef, thinly sliced
• 1 batch of caramelized onions, see above
• finely chopped parsley, for garnish
• 1 batch of au jus dipping sauce, see below
• 1 1/2 tbsp unsalted butter
• 1 tbsp flour
• 1 cup(s) low-sodium beef broth
• 1 shallot, finely chopped
• 2 garlic cloves, finely minced
• 1/4 tsp dried thyme