Prepare the beef: Pat the beef cubes dry with paper towels (moisture prevents browning). Season generously with kosher salt and black pepper. Toss the beef in flour until evenly coated.
~2 lbs. well-marbled beef chuck, kosher salt & freshly ground black pepper, 3 Tbsp. all-purpose flour
Sear for flavor: In a large skillet over medium-high heat, heat oil until shimmering. In batches, sear the beef until browned on all sides (about 1 minute per side). Transfer browned beef to the base of a 6-quart slow cooker.
2 Tbsp. olive oil or vegetable oil
Layer the vegetables: Scatter the onions, garlic, carrots, celery, and potatoes evenly over the seared beef.
1 large yellow onion, 4 garlic cloves, 4 carrots, 3-4 celery stalks, 1 lb. golden baby potatoes
Build the broth: In a mixing bowl, whisk together the tomato paste, red wine, beef broth, Worcestershire sauce, Dijon mustard, Balsamic vinegar, and herbs (thyme, rosemary, parsley). Season with a pinch more salt and pepper. Pour this mixture over the meat and vegetables. Nestle in the bay leaves.
3 Tbsp. tomato paste, 1 cup dry red wine, 4 cups low-sodium beef broth, 2 Tbsp. Worcestershire sauce, 1 Tbsp. dijon mustard, 1 Tbsp. balsamic vinegar, 1 tbsp each: chopped fresh thyme, rosemary, and parsley, 2 bay leaves
Slow cook: Cover and cook on low for 8–10 hoursStart Timer, or until beef is fork-tender and vegetables are meltingly soft.
Thicken stew: Combine the cornstarch and water to make the slurry. Add slurry and frozen peas into the slow cooker and replace the lid until the stew thickens, about ~15 minutes.
1/2 cup frozen peas, 2 tbsp cornstarch + 3 tbsp cold water
Add butter: Then, just before serving, add in the cold butter and stir for a rich, silky finish.
3 tbsp cold, unsalted butter
Serve & garnish: Ladle into warm bowls. Top with chopped chives or parsley. Serve with crusty bread or over creamy mashed potatoes for a heartier meal.
chopped chives or fresh parsley