beer & beef slow-cooker stew

Ingredients

• 2 pounds stewing beef
• 2 tablespoons olive oil
• 2 tablespoons butter
• 2 stalks celery, chopped
• 2 large carrots, chopped
• 1 pound potatoes, chopped
• 2 cloves garlic, chopped
• 2 - bay leaves
• 1 tablespoon parsley, dried
• 1 cup dark beer
• 1 cup beef stock
• 1 can diced tomatoes with green chilis
• 2 teaspoons salt
• 1 teaspoon pepper