Add the onion, beef, garlic, salt, pepper, paprika, cayenne, broth, and tomato paste to a 6-quart slow cooker pan.
Gently mix everything together.
Cover and cook on HIGH for 3 hours. You can also cook on LOW for 7 hours.
When done, whisk the cornstarch with water until smooth. Stir the slurry into the beef mixture. If you cooked the goulash on high, the stew should thicken immediately. If you cooked it on low, or if it doesn't thicken right away, set the slow cooker to high, cover, and cook for 15-30 more minutes, until the stew thickens.
Serve immediately.
Video
Notes
The paprika used in this recipe is sweet paprika, not spicy or smoky. It adds warmth and depth of flavor to the dish.
Since we're using a significant amount of paprika, it's important to make sure it's very fresh. Check the date on the jar, and buy a new one if yours has been open for many months.
The nutrition info assumes that the meat has been trimmed of separable fat.
This recipe was written for 2 pounds of meat. If your chuck roast is larger, say, 3 pounds, you'll need to cook the stew for 4 hours on HIGH (8 hours on LOW). You should also add more seasonings and liquids - I recommend adding an extra tablespoon of paprika and half a cup of broth.
As with most stews, the leftovers are delicious. You can keep them in an airtight container in the fridge for up to 4 days. Reheat them covered in the microwave at 50% power to avoid drying the meat.