French Onion Dip with Glazed Onions - Michigan Onion

Ingredients

• 1 cup yellow onion, minced
• 3 cups beef broth
• 2 tablespoons unsalted butter
• 2 tablespoons Canola oil
• 3 pounds onions, sliced
• 1 cup onions, precooked from above
• 1/3 cup sherry vinegar
• 12 8-10 inch French rolls
• 1/2 cup horseradish dijon mustard
• 1 1/2 pounds roast beef slices
• 3 cups cheese, emmental, grated (could substitute with Swiss cheese or Gruyére)