Preheat empty slow cooker on high heat with lid on.
Season roast with salt and pepper.
Heat oil in a skillet and brown roast on all sides; transfer to slow cooker.
Add onions and carrots.
Add garlic, mushrooms, 1 cup broth or stock and tomato paste.
Add flour to remaining cup of broth/stock; mix thoroughly and add to slow cooker.
Cover; reduce heat to low and cook 6 hours or overnight.
Roast is done when it can be easily pulled apart.
Place roast and gravy in a serving bowl and garnish with chopped parsley.