Wash and dry the potatoes, leaving the skin on, cut the potatoes into fries, not too skinny, and make sure they are all roughly the same.

Place them in a large bowl and cover with cold water, leave to soak for at least 30 minutes longer if possible, I usually let them soak for 2 hours if I can.

Pre heat the oven to 180 degrees C, I use and electric, fan assisted oven, please adjust according to your own oven.

While the fries are soaking make the aioli.

Add the egg yolks with the salt to a large mixing bowl and whisk for about 2 minutes. Slowly start adding the grapeseed oil, start off by adding half a teaspoon at a time then as the eggs and oil emulsifies then add the rest of the oil in a slow trickle, whisking all the time. Follow on with the olive oil. You should have a smooth, shiny consistency.

Then stir in the mustard and juice and whisk for about 1 minute, finally stir in the garlic. Cover and keep in the fridge until you are ready to use.

Drain the fries in a colander and rinse in cold water. Dry the fries with a clean tea cloth, the dryer they are the better.

Line a baking tray with parchment paper, add the fries, black pepper, sea salt, rosemary and oil, using your hands mix everything together making sure the fries are covered in the oil, rosemary and seasoning.

Place in the middle of the oven and bake for 30 - 35 minutes, checking half way through, give the tray a little shake.

When the fries are golden brown remove them from the oven and place on kitchen paper to drain off any excess oil.

Serve hot with the aioli.