Crumble up the black pudding, roll it into golf ball sized balls.
Make the pastry
Heat the butter and water together, mix in the flour and cook it out, slowly beat in the eggs.
Leave to cool.
Wrap the pastry around the black pudding ball evenly and set aside ready to fry, heat the fryer to 180°C.
Make the remoulade, julienne slice the apple and celeriac and juice the lemon onto it to stop it going brown. Mix in the mayo and mustard.
Make the meringue
Boil the sugar and water to a softball stage.
Whisk the whites to soft peak stage and slowly whisk in the sugar and add the chopped tarragon and Dijon mustard.
Deep fry the doughnut until golden brown on the outside and warm in the middle