HOW TO MAKE BY HAND
1Use a chef’s knife to mince the garlic and anchovies finely. Using the side of the knife, mash them into a paste by pushing and pulling the mound of anchovies and garlic across the cutting board (see video). Set aside.
2Whisk the egg yolk, lemon juice, and mustard in a medium bowl until frothy. Placing a dishcloth underneath the bowl helps to steady it as you whisk.
3Get into a comfortable whisking position, and while you whisk with one hand, slowly stream the oil into the bowl with the other hand. You are looking to add the oil in tiny drips and will notice that as you whisk in the oil, the mixture in the bowl will start to lighten in color and thicken.
4When all of the oil is added, check the consistency. If it’s too thick, whisk in a teaspoon or so of water. If it’s too thin, continue to whisk and stream in a bit more oil.
5Finish by whisking in the mashed anchovies, garlic, and parmesan cheese. Then, taste and generously season with salt and pepper.
MAKE WITH A BLENDER OR FOOD PROCESSOR
1Combine anchovies, garlic, egg yolk, lemon juice, mustard, and parmesan cheese in the bottom of a blender or food processor bowl. When using a food processor, if you have a small bowl attachment for your food processor, use it.
2With the blender or processor running, slowly drizzle in the oil until a smooth dressing forms. If it seems too thick after adding all of the oil, add a teaspoon or so of water to thin it out. If it is too thin, slowly drizzle in a bit more oil with the machine on. Taste and generously season with salt and pepper.
MAKE WITH AN IMMERSION BLENDER
1Combine all the ingredients at the bottom of a cup that fits the head of an immersion blender. Blend, slowly pulling the blender up and then back down again to incorporate all the ingredients into the oil.
2If after adding all of the oil, it seems too thick, add a teaspoon or so of water to thin it out. If it is too thin, with the machine on, slowly drizzle in a bit more oil. Taste and generously season with salt and pepper.