Season and dredge the beef. Pat the beef dry. Season generously with salt and pepper.
Toss with flour until lightly coated, shaking off excess.
Sear in batches. Heat oil in a large skillet over medium-high. Sear beef on two sides until browned, about 2–3 minutes per side. Don’t overcrowd the pan.
Transfer seared beef to the slow cooker.
Sauté aromatics. In the same skillet, add a bit more oil if needed. Sauté onion and celery with a pinch of salt for 3–4 minutes until softened. Stir in garlic and tomato paste; cook 1 minute until fragrant and darkened.
Transfer to the slow cooker.
Deglaze. Pour the wine into the hot skillet, scraping up browned bits. Let it simmer 1–2 minutes. Pour into the slow cooker.
If skipping wine, use a splash of broth.
Load the pot. Add carrots, potatoes, Worcestershire, thyme, rosemary, paprika, bay leaves, and beef broth. Stir gently to combine.
Cook low and slow. Cover and cook on Low for 8–10 hours (best for tenderness) or High for 4–5 hours, until beef is fork-tender and vegetables are soft but not mushy.
Finish and thicken. Stir in peas during the last 10 minutes. If you want a thicker stew, mix cornstarch with water and stir it in.
Let it bubble in the slow cooker for 10–15 minutes until slightly thickened.
Taste and adjust. Remove bay leaves. Taste and adjust salt, pepper, and acidity. A splash of Worcestershire or a squeeze of lemon can brighten flavors.
Serve. Ladle into bowls and top with chopped parsley.
Serve with crusty bread or over buttered noodles if you like.