Season the steak on both sides. Heat the oil in a pan until smoking hot. Reduce the heat and cook for 2 to 3 minutes on each side. Remove from the heat and leave to rest for a couple of minutes.
Preheat the oven to 200'C.
Peel the shallots and cut them in half lengthways. Heat the butter in a pan until bubbling, fry the shallots for a minute, add the sugar and colour until golden brown. De-glaze the pan with the chicken stock and transfer to the oven and cook for 10 minutes.
Mince the garlic cloves with a pinch of salt. Zest and juice the lemon. Mix with the egg yolk and mustard. Slowly start whisking in the oil until the mixture starts to thicken. Once thickened, pour a little faster whilst always whisking to make sure the mixture does not split.
Place the shallots in the middle of the plate, slice the steak into 3 pieces and then place on top. Drizzle the cooking liquor from the shallots around and then finish with a dollop of the aioli. Serve the chips either on the side or in a little bowl.
Using a mandoline, cut the potatoes into a fine julienne over a bowl of cold water. The water will prevent the potatoes from turning brown, and will remove any excess starch.
Meanwhile heat the frying oil in a deep fat fryer to 180'C. if you do not have a deep fat fryer, place the oil in a deep pot: the oil is ready for frying when a bamboo skewer or a wooden spoon placed in the oil sizzles wildly.
Drain the potato matchsticks. Squeeze out any excess water, and dry with paper towels.
When the fryer oil is hot enough, drop the potatoes in small handfuls, and use tongs or a wooden spoon to stir the matchstick about: you do not want the potatoes to clump up into a pancake.
When the potatoes are golden remove from the oil, and drain on some paper towels. Season with salt.
«Finish off your aioli with different types of oil such as olive or avocado for a slightly richer flavor.»