Best French Onion Beef Dip Sandwiches Recipe

Ingredients

• 2 Tbsp olive oil
• ⅓ cup unsalted butter
• 4 large sweet or yellow onions, thinly sliced lengthwise
• Salt, to taste
• Pepper, to taste
• ½ cup cooking sherry or dry red wine
• 5 cups beef stock
• 2 beef bouillon cubes
• 1 Tbsp Worcestershire
• 3 thyme sprigs
• 1 Tbsp sherry vinegar
• 2 lb sirloin tip roast
• 1 Tbsp chopped rosemary
• 1 Tbsp chopped thyme leaves
• 2 cloves garlic, minced
• ½ tsp kosher salt
• ¼ tsp pepper
• 1 medium onion, sliced into ½-inch rings
• Kosher salt, to taste
• 1 cup mayonnaise
• 3-4 Tbsp prepared horseradish (adjust based on strength of horseradish)
• 1 Tbsp chopped chives, optional
• 2 tsp grainy Dijon mustard
• 2 tsp lemon juice
• White sandwich rolls, such as ciabatta or Portuguese rolls
• Sliced gruyere or provolone cheese