Peel and chop the vegetables, then put them in a pan of lightly salted water. Bring to the boil and simmer for about 15 minutes, until they are tender.
Shred or thinly slice the cabbage and add to the vegetables for the last 2 minutes of cooking.
Drain, then put them back in the pan and lightly mash them with a fork or potato masher. Season with salt and pepper and mix in some dairy-free spread or butter. Keep warm.
Chop the sausages into 2 cm pieces, then fry them in the oil with onion for 2-3 minutes. Add the thyme, stir for a few seconds, then add the mashed vegetables.
Cook for a couple of minutes, stirring occasionally.
Serve warm.