Step 1

In a 5- to 6-quart slow cooker, stir together cornstarch and 2 tablespoons broth until smooth. Add remaining broth, tomato paste, potatoes, carrots, onion, and Worcestershire. Season with salt and pepper and toss.

Step 2

Season roast with 1 teaspoon salt and 1/2 teaspoon pepper, and rub with garlic. Place on top of vegetables. Cover and cook on high until roast is fork-tender, 5 hours (or 8 hours on low).

Step 3

Transfer roast to a cutting board; thinly slice against the grain. Place vegetables in a serving dish; skim fat from pan juices, then pour through a fine-mesh sieve, if desired. Serve roast and vegetables drizzled with juices.