Toss beef with salt, pepper, and flour until lightly coated.
Heat oil in a skillet. Brown beef in batches, then transfer to the slow cooker.
Add onion, carrots, celery, potatoes, and garlic to the cooker. Stir to combine.
Whisk broth, tomato paste, Worcestershire, soy sauce, thyme, rosemary, and paprika. Pour over contents.
Cover and cook on Low 7–8 hours or High 4–5 hours, until beef is tender.
Stir cornstarch with cold water. Mix into stew and add peas. Cook 15–20 minutes.
Taste and adjust seasoning. Garnish with parsley and serve warm.