Turn up the heat and add the white wine, stirring continuously.

Return to heat and gradually add half the stock, stirring continuously.

Add the sauce and cook for 3 to 4 minutes, stirring continuously, to heat through.

Increase the heat to high, add the shells and cook for four minutes stirring continuously.

Stir continuously until rice is toasted to a light brown.

Bring to the boil, stirring continuously, then remove from the heat and season to taste.

Add a good ladleful of the hot stock and stir continuously.

Continue adding more stock, stirring continuously, until the rice is cooked.

Whisk in the lemon juice, a little bit at a time, stirring continuously.

Turn the heat up to medium and stir continuously.