Slow Cooker Pot Roast

Ingredients:
3-1/2 lb chuck roast
1 Large Onion
10 Cloves of Garlic
2 Carrots, peeled and diced
2 Stalks of Celery, diced
10oz of Beer (budwiser or yengling)
1/2 cup of Beef Stock
Dash of Worcesteshire Sauce
1 Sprig of Fresh Rosemary
1 Sprig of Fresh Thyme
1 Tbsp of Granulated Onion
1/2 cup of Flour
About 3 Tbsp of Vegetable Oil
Salt and Pepper, to taste