Cube the beef and place in a sealable container or bag. Prepare garlic, celery, onion, carrot, and parsnips and add to the container. Add Worcestershire sauce, salt, pepper, and Italian seasoning. Seal and refrigerate until ready to cook.
Place contents of bag into Instant Pot with beef broth. Stir well.
Cover and seal the lid and pressure valve. Cook on Manual High for 20 minutes, allowing a natural pressure release. When pressure valve drops, remove the lid.
Hit saute and stir in xantham gum. Allow the stew to come to a boil and thicken, 4-5 minutes, then taste and adjust seasoning with salt and pepper if necessary. Serve hot garnished with fresh parsley.
*Nutritional information is an estimate. Please consult a doctor or nutritionist for the most accurate nutritional info.