Heat a large frying pan over medium high heat. Add olive oil. Season beef on both sides with salt and pepper. Brown beef in frying pan, 5 minutes on each side.
While beef is cooking, put onions, carrots, parsnips, mushrooms, thyme, bay, garlic and seasoning in 6 quart crock pot. (I used Penzey's Old World, which is a blend of spices including paprika, dill, celery salt, garlic, and more. But this will be good with whatever seasoning blend you like!)
When beef is browned, put in crock on top of veggies. Add beef broth and Worcestershire sauce. Cook on low for 8 hours.
Remove meat and vegetables from crock. Strain/skim broth. Add cornstarch to broth, put in small saucepan, and bring to boil to thicken.