Peel then dice the celeriac. Finely chop the onion and garlic. Roughly chop the cauliflower.
Heat the oil in a saucepan, then sauté the onion for 5 minutes.
Add the garlic and caraway seeds, then stir for a few seconds.
Add the chopped veggies, then pour over the stock, enough to cover the veggies. Add the bay leaf.
Bring to a boil, cover, then simmer for 15-20 minutes, until the veggies are tender.
Remove the bay leaf, then using a stick blender, process the soup until it's smooth and silky.
Add the drained beans. You can whiz it again, or leave it as rustic. Add more stock, if you think it's too thick.
Serve with a dash of apple cider vinegar and some freshly parsley scattered on top.