1. In a large skillet, heat the olive oil over medium-high heat. Add the beef tips and brown them on all sides, which will give your dish a richer flavor. Transfer them into the slow cooker.
2. To the same skillet, add the diced onion and sauté until it’s soft and translucent, about 3 minutes. Add the minced garlic and sauté for an additional minute, just until fragrant. Spoon this mixture over the beef in the slow cooker.
3. In the slow cooker, pour in beef broth, balsamic vinegar, Worcestershire sauce, and soy sauce. Stir in the rosemary, black pepper, and salt.
4. Cover and cook on low for 7-8 hours or on high for 3-4 hours, until the beef is tender and falls apart easily.
5. About 30 minutes before serving, mix cornstarch and cold water in a small bowl until smooth. Stir the mixture into the slow cooker to thicken the sauce.
6. Let it cook for another 25-30 minutes. Then, give everything a good stir, adjust the seasoning to your taste, and serve warm.

Variations & Tips
– For families with picky eaters, you can make the beef tips without the rosemary and serve the herb on the side for those who enjoy the extra flavor.
– Feel free to add in some carrots or mushrooms during the last 2 hours of cooking if you’re looking to sneak some veggies into the meal.
– If you prefer a gluten-free version, make sure to use a gluten-free soy sauce and serve the beef tips over cauliflower mash or rice.
– To save time in the morning, you can brown the meat and onions the night before, refrigerate them overnight, and then place them in the slow cooker with the other ingredients in the morning.
– And finally, if you happen to have leftovers, beef tips are wonderful when repurposed into a beef pot pie or a hearty beef tip and noodle soup the next day.