Layer the vegetables. Place the potatoes, carrots, and onion in the slow cooker. Pat the thawed beef dry and season it with the measured salt and pepper. Keep the pieces roughly equal in size.

Brown in batches. Heat the oil in a large skillet over medium-high heat. Brown the beef in two or three batches, turning to color several sides without trying to cook it through. Transfer each batch to the cooker.

Deglaze the pan. Lower the heat and stir the garlic and tomato paste into the skillet for about 30 seconds. Pour in a little of the measured broth and scrape up the browned bits. Add this mixture to the cooker with the remaining broth, Worcestershire sauce, thyme, and bay leaf.

Cook until fork-tender. Cover and cook on LOW for about 8–9 hours or HIGH for 4½–5½ hours. The potatoes should be tender and the beef should yield easily to a fork. For whole-muscle beef, 145°F (63°C) plus a 3-minute rest is the minimum safety standard; chuck stew needs substantially longer cooking for tenderness.

Thicken and add peas. Remove the bay leaf. Stir the cornstarch slurry again, then gently mix it into the hot liquid with the thawed peas. Cover on HIGH for 15–20 minutes, until the gravy thickens and the peas are hot. A saucepan can be used if the cooker does not simmer enough.

Check seasoning. Gently fold the stew rather than stirring aggressively, which can break up the potatoes. Taste the gravy and adjust salt or pepper. Ladle the meat, vegetables, and gravy into six bowls.