Slow Cooker Pot Roast

Name: Slow Cooker Pot Roast
Ingredients: 1 (4 pound) beef roast (such as chuck, eye of round, etc.); salt and pepper to taste; 1 onion, sliced; 4 cloves garlic, chopped; 1 tablespoon fresh rosemary, chopped (or 1/2 tablespoon dried rosemary); 1 teaspoon fresh thyme, chopped (or 1/2 teaspoon dried thyme); 1 cup beef broth; 2 tablespoons flour (rice flour for gluten-free); 1 teaspoon dijon mustard (optional); 1 tablespoon Worcestershire sauce; 2 teaspoons black pepper, coarsely ground; salt to taste