- Thinly slice the white and light green parts of the leek into 3-inch-long julienne strips. Rinse in a bowl of water to remove the grit, drain, and pat dry. 
- Add the oil to a medium saucepan to a depth of 25mm/1 inch and heat to 190°C/375°F. 
- Add a small handful of the leeks to the oil. (Caution: the oil will bubble up immediately. Always fry in small batches to avoid overcrowding the pan and to prevent boil-overs.) 
- Fry the leeks, stirring often with a metal slotted spoon, until the oil is barely bubbling and the leeks are light golden brown, 1 to 3 minutes. (The oil temperature will drop when you add the leeks; let it return to the starting temperature before frying the next batch.) 
- Lift the leeks from the oil using the slotted spoon, tap against the side of the pan to drain off excess oil, and transfer to a large plate lined with a couple of layers of paper towel. Gently shake on the paper towel and then slide the leeks onto the paper towel below it, discarding the oil-soaked top layer. 
- Sprinkle the leeks lightly with salt while they’re still hot. Let cool to room temperature before using as a garnish.