French Dip Sandwich with Spicy Horseradish Mayo

Ingredients

• 1/3 cup soy sauce
• 3 tablespoons olive oil
• 3 tablespoons Worcestershire sauce
• 2 tablespoons balsamic vinegar
• 1 tablespoon honey
• 2 smashed garlic cloves
• 1 1/2 - 2 pound flank steak
• Fresh cracked black pepper
• Olive oil or vegetable oil
• 1 large onion, peeled and thinly sliced
• 1 tablespoon unsalted butter
• Salt
• pepper
• 4 6-inch French or hoagie rolls, sliced in half horizontally
• 2 cups beef stock
• 1/4 teaspoon garlic powder
• 1/4 teaspoon onion powder
• 1/4 teaspoon dried thyme
• 1 tablespoon Worcestershire sauce
• 3/4 cup Duke’s Mayonnaise
• 2-3 tablespoons prepared horseradish (according to your taste)
• 1 tablespoon finely chopped chives (optional)
• 1 tablespoon Dijon mustard
• 2 teaspoons lemon juice