Slow Cooker Beef and Guinness Stew

Name: Slow Cooker Beef and Guinness Stew
Prep time: 30 min
Cook time: 8 h
Total time: 8 h 30 min
Cuisine: British
Ingredients: 2.5 pounds beef chuck; 3 celery sticks; 1 big sweet onion or regular one or 2 medium-sized onions; 3-4 medium-sized potatoes; 3 big carrots; 33 fl oz low sodium beef stock; 12 ounce bottle Guinness beer (stout or draught); ½ cup white flour; 3 garlic cloves; 2 bay leaves; 4 tablespoons olive oil (divided); 4 sprigs of fresh thyme (or 2 teaspoons dried); Freshly cracked black pepper to taste; Salt to taste