French Dipped Sandwiches

Name: French Dipped Sandwiches
Ingredients: 1 small onion, roughly chopped; 1 small carrot, roughly chopped; 1 stalk celery, roughly chopped; 1 small leek, white and light-green parts only, roughly chopped; 2 cloves garlic, chopped; 1 sprig fresh thyme; 1/4 teaspoon dried sage; 1/4 teaspoon dried oregano; 1/4 teaspoon ground nutmeg; 1/2 teaspoon ground cloves; 1/2 teaspoon ground allspice; 2 pounds beef top round roast; Salt and freshly ground pepper; 2 cups beef broth; 6 French rolls; Hot mustard, for serving