Season the beef chunks liberally with salt and pepper.
I like to brown my meat before adding it to the slow cooker (the browned edges gives more flavor), but this is optional: in a skillet over medium high heat, add some vegetable oil and brown the beef chunks on all sides until a deep golden brown color, about 6-8 minutes total.
Add the beef, onion, celery, garlic, mixed veggies, potatoes, tomato soup, broth, bouillon base, and worcestershire sauce to your slow cooker. Season with additional salt and pepper.
Stir, cover, and cook on low for 7-9 hours or on high for 4-5 hours.