Creating Slow Cooker Broccoli Beef is simple if you follow these detailed steps:

1. Prepare the Beef: Slice the flank steak thinly against the grain. This helps ensure tenderness when cooked.
2. Make the Sauce: In a bowl, mix soy sauce, brown sugar, cornstarch, minced garlic, minced ginger, sesame oil, and black pepper. Whisk until combined.
3. Brown the Beef: (Optional) In a skillet, heat vegetable oil over medium-high heat. Add the beef slices in batches and brown for about 2-3 minutes. This step adds depth to the flavor but can be skipped for quicker preparation.
4. Transfer to Slow Cooker: Place the browned or raw beef into the slow cooker. Pour the sauce mixture over the beef, ensuring all slices are coated.
5. Cook: Cover the slow cooker and set it on low for 4 to 6 hours or high for 2 to 3 hours. Stir occasionally to ensure the beef absorbs all the flavors.
6. Add Broccoli: About 30 minutes before serving, add the fresh broccoli florets. This will keep them vibrant and slightly crisp.
7. Thicken the Sauce: If you prefer a thicker sauce, mix an additional tablespoon of cornstarch with a small amount of cold water. Stir into the slow cooker during the last 15 minutes of cooking.
8. Taste and Adjust: Before serving, taste the dish. Adjust the seasoning if necessary, adding more soy sauce or brown sugar to your preference.
9. Serve Hot: Once cooked, serve the Beef and Broccoli over rice or noodles for a complete meal.

Following these steps will guide you to an incredible Slow Cooker Broccoli Beef that is sure to impress!