Instructions:
- Prep the Beef: In a large bowl, toss the cubed beef with flour, salt, and pepper until lightly coated.
- Sear for Flavour: Heat olive oil in a heavy-bottomed skillet over medium-high heat. Working in batches, sear the beef on all sides until deeply browned. Remove seared beef and set aside.
- Build the Base: Reduce heat slightly. Add the chopped onion to the pan drippings and sauté for 5 minutes until softened. Add minced garlic and tomato paste; cook for 1 minute until fragrant.
- Deglaze: Pour in the red wine (if using) and scrape up any browned bits stuck to the bottom of the pan. Let the wine bubble and reduce by half (about 3 minutes).
- Combine in Slow Cooker: Transfer the seared beef, the onion/wine mixture, beef broth, Worcestershire sauce, rosemary, thyme, and bay leaves into the slow cooker insert. Stir well.
- Slow Cook: Cover and cook on Low for 6 hours.
- Add Vegetables: After 6 hours, add the potatoes, carrots, and celery to the slow cooker. Stir gently. Cover and continue cooking on Low for another 2 hours, or until the vegetables are fork-tender and the beef shreds easily.
- Thicken the Gravy: Remove the herb sprigs and bay leaves. In a small bowl, whisk the cornstarch and cold water together until smooth (the slurry). Stir the slurry into the stew.
- Final Cook & Finish: Cover and cook on High for 15-20 minutes, or until the stew has visibly thickened. Stir in the frozen peas during the last 5 minutes of cooking.
- Rest and Serve: Allow the stew to rest for 10 minutes before serving hot.