Heat a large skillet over medium heat on the stovetop. As it warms, toss the cut beef with ⅓ cup flour either in a mixing bowl or sealed bag.
Once the skillet is hot, add 2 tablespoons of olive oil and brown the meat. Once browned on each side, transfer to the slow cooker.
In the same skillet, saute onion and garlic for 1-2 minutes. Add to the slow cooker along with the beef broth, potatoes, carrots, parsnips, seasoning, and Worcestershire sauce.
Cook the stew on low for 8-10 hours. At the last half hour, stir in the frozen peas and flour slurry.
Place the lid back on and let continue cooking for 30 minutes.