The tian cooks better if made in shallow layers in two dishes – if you prepare it a day ahead, just add the liquid an hour before cooking.
2 small sweet potatoes
2 medium potatoes
1 small celeriac, about 300g/10oz
2 small parsnips
4 tbsp olive oil, plus extra for greasing
2–3 tbsp chopped fresh parsley, plus extra to garnish
salt and freshly grated black pepper, to season
Takes 1 hour 40 minutes • Serves 12 (easily halved)
1 Preheat the oven to 200°C/Gas 6/fan oven 180°C. Peel all the vegetables, then thinly slice with a mandolin, in a food processor or by hand.
2 Blanch the vegetable slices in a pan of boiling salted water for 3–5 minutes (no longer or they will break up). Drain, reserving some of the cooking liquid, and refresh under cold running water.
3 Oil two 25cm/10in dishes. Layer the vegetables and between each layer, sprinkle over the parsley, some salt and pepper and drizzle with oil. Pour in just enough reserved liquid to cover the first layer of vegetables. Cover loosely with a double sheet of oiled greaseproof paper. Bake for 30 minutes, uncover and cook 30 minutes more until tender and golden. Garnish with parsley.
• Per serving 101 kcals, protein 2g, carbohydrate 15g, fat 4g, saturated fat 1g, fibre 3g, added sugar trace, salt 0.35g