Finely chop the onion and garlic.
Shred the cabbage. Peel the potatoes and celeriac, then cut them roughly into 3cm chunks.
Heat 1 Tbsp olive oil in a large pan, then gently sauté the garlic and onion for about 5 minutes until translucent. Add the potatoes and celeriac and stir for a couple of minutes.
Add the vegetable stock, bring to the boil and simmer for 20 minutes until the potatoes are tender. Add the shredded cabbage and cook for another 5-10 minutes.
Remove the bay leaf, add the cider vinegar and serve.