French Onion Chuck Roast

食材

3 ½ chuck roast

3 yellow onions, thinly sliced

4 garlic cloves

1 tbsp butter

1 tbsp Worcestershire

1 tbsp balsamic vinegar

1 tbsp tomato paste

2 cups beef broth

Salt & Pepper

1 tsp black pepper

1 tsp dried thyme

1 tbsp Dijon mustard

3-4oz finely shredded gruyere (or Swiss)