Cut beef into cubes and toss with salt, pepper, and flour.
Sear beef in batches in hot oil, 45 seconds per side.
Transfer to slow cooker.
Sauté onions in butter, add garlic, deglaze with wine.
Pour into slow cooker.
Add broth, bouillon, Worcestershire, tomato paste, carrots, potatoes, bay leaves, and rosemary.
Cook on low 7.5–8 hrs or high 3.5–4 hrs.
Add peas last 15 minutes.
Optional: mix cornstarch + water and stir in to thicken.
Swirl in butter before serving.
