Slow-Cooker Red Wine Beef Stew

In a large mixing bowl, pat beef dry with a paper towel. Season generously with salt and pepper. Preheat a large skillet over medium-high heat. Drizzle with oil and sear meat on all sides until golden brown with a crust, about 10 minutes. Transfer meat to the slow cooker. Add butter and scrape the pan with a wooden spoon to loosen all browned meat bits. Stir in red wine and tomato paste; simmer for 1 minute then transfer to the slow cooker. Add remaining ingredients to slow cooker, then season with salt and cook on low until meat is tender, 6 to 8 hours. Remove stalk of rosemary. Garnish with parsley and serve immediately.