Pat the beef dry. Season with salt and pepper, then toss with the flour to coat lightly.
Heat the oil in a large skillet over medium-high. Brown the beef in batches until crusty. Transfer to the slow cooker.
Add onion, celery, and carrots to the skillet. Cook until softened, 4–5 minutes. Stir in garlic for 30 seconds.
Mix in tomato paste and cook until it darkens slightly. Pour in wine and scrape up browned bits; simmer 1 minute.
Tip skillet contents into the slow cooker. Add broth, Worcestershire, soy, potatoes, thyme, rosemary, and paprika. Stir well.
Cover and cook on Low 7–8 hours or High 4–5 hours, until the beef is very tender.
Skim fat. Whisk cornstarch with water and stir into the stew. Cook on High 15–20 minutes to thicken.
Stir in peas and parsley. Rest 5 minutes, then taste and adjust seasoning before serving.