Chop the Vegetables: Dice the potatoes, carrots, celery, and onion into uniform pieces. Add these vegetables to the crock pot.
Add Broth and Seasoning: Pour the beef broth into the crock pot and stir in minced garlic, salt, and pepper. Mix well to combine.
Cook Low and Slow: Cover the crock pot and set it on low for 6-8 hours, or on high for 3-4 hours. Stir occasionally, if possible.
Blend for Creaminess: Once the cooking time is up, stir in the milk. For a creamier texture, blend a portion of the soup with an immersion blender before adding the milk.
Adjust the Seasoning: Taste the soup and adjust salt and pepper as necessary before serving.
Notes
This soup refrigerates well and can be frozen for up to 3 months.