1. For the potato 'risotto' sweat off the leeks with the butter, a pinch of salt and any additional ingredients for about 3 to 4mins until soft.
2. Add the potatoes and mix.
3. Add the stock a tiny bit at a time until absorbed and add again. Keep stirring to draw out starch.
4. When the potatoes are almost cooked and quite dry quickly remove from the pan and add the parsley and parmesan.
5. Place in blast chiller or fridge for a couple of hours or overnight until firm and cool.
6. Roll the potatoes into balls and put in the seasoned flour, then roll in the egg and finally in the breadcrumbs.
7. Fry until golden brown.
8. For the burnt leek mayonnaise, firstly heat a griddle pan until it is smoking, add the leeks and a splash of oil and fry for about 5 to 10 minutes until black all over.
9. Blend the leeks with the water or stock until smooth and chill.
10. Put the egg yolks in a bowl and very slowly add the vegetable oil, whisking as you go.
11. Season with salt, pepper and vinegar and then add the cold leek mixture.
12. Serve the arancinis on a plate with some blanched leek, the mayonnaise and some crispy fried leek (optional)
The mayonnaise can be kept for a week. The aranchini mix is best if made the night before so it is firm and ready to be rolled the next day.