To a slow cooker insert, add the beef chunks. (You can brown them first if you want, but it will be fine if you don't. This is easy if you use and instant pot-- brown first, then add the rest of the ingredients and switch to slow cook mode.))
Add the garlic, mushrooms, and frozen or freshly chopped vegetables.
Pout the sauce over the top, stir, cover, and cook on low for 6-8 hours.
When ready to serve, taste and adjust salt and seasonings as needed.
Serve plain, or with shredded Parmesan, sour cream, fresh chopped onion or basil, pesto, or any other garnish you like.