Squeeze the juice of 1 lemon into a large bowl of cold water. Peel the Jerusalem artichokes, and drop them immediately into the acidulated water to prevent discoloration.

When they are all prepared, drain, dry and cut into 1/4 in (1/2 cm) dice.

Sweat the chopped shallot in 1/2 oz (15 g) of the butter and 1 tbsp oil, add the diced artichokes, sprinkle with a pinch of salt and cook over a low heat, stirring, for 2 - 3 minutes.

Add the stock, bring slowly to the boil, cover and simmer gently for about 10 minutes or until they are tender but not at all mushy. Set aside.

Place the vol-au-vent cases in the oven, preheated to 325°F (170°C) mark 3, for 15 minutes.

While they are heating make the sauce. Melt the remaining butter in a small saucepan and fry the chilli pepper gently for 1 minute. Add the tomato puree and continue stirring over the low heat for about 2 minutes.

Stir in 7 fl oz (200 ml) boiling hot water and simmer, uncovered, over a slightly higher heat for 2 - 3 minutes. Stir in the cream and a pinch of salt; simmer, stirring continuously, for a further 2 - 3 minutes.

Add this rather thin sauce to the artichokes and place them over a low heat, stirring carefully without breaking them up.

When they are very hot, turn off the heat, add the remaining lemon juice, a little more salt if needed and stir once more.

Fill the pastry cases with this mixture, put their lids on top and serve at once on very hot plates