In a 6-quart to 8-quart crock pot, combine the potatoes, cauliflower, beans, onion, garlic, vegetable stock, butter, wine, thyme, garlic powder and 1-½ teaspoons kosher salt; cover, set to low heat and cook until the vegetables are very tender.
Remove and discard the thyme sprig and turn off the crock pot.
Add the lemon juice.
To make a completely smooth and creamy soup, purée the ingredients using an immersion blender; alternatively, purée the soup in a blender in two batches, transferring the puréed soup to a different pot.
To make a textured, chunky soup, smash the ingredients using a potato masher in the slow cooker.
Stir in the sour cream and chives; taste and add additional salt if necessary.
Serve in bowls topped with black pepper, crushed potato chips and shredded Cheddar.
