Peel the potatoes, carrots and celeriac and cut into 1.5 cm cubes. Place the potatoes in a bowl of cold water for approximately 5 minutes.
Thinly slice the shallots and gently fry in a little butter until golden brown. Add the paprika and wine and leave to simmer. Peel and finely chop the garlic. Halve the chillies lengthways, remove the seeds and pith and cut into strips. Add the garlic, chillies, thyme leaves and lemon zest to the pan and top up with the vegetable stock. Bring to the boil and season with salt, pepper and ground caraway to taste.
Have a large dish ready. Cut a sheet of SAGA Cooking Paper so that it is about 2 cm larger than the rim of the dish. Layer the drained potatoes, carrots, celeriac in the dish and add the stock.
After brushing the edges with egg white, cover the dish with the cooking paper and seal it by folding the edges over the rim of the dish and pressing all round.
Cook in the oven for 25-35 minutes at 170°C (190°C). Serve the dish with its paper cover to retain the aroma until the last minute. Serve the goulash with rye bread crisps.