Zest and juice the lemon. You'll need about 3 Tbsp juice and 1 tsp lemon zest. Mince the garlic and anchovy filets. Reserve about ½ tsp of the oil from the anchovy container.
Add the lemon juice, zest, minced garlic, minced anchovies, anchovy oil, and pepper to a bowl. Whisk to combine.
Add the Dijon, mayonnaise, and grated Parmesan and whisk to combine again. Taste the dressing and adjust the ingredients to your liking. Serve with a fresh salad or you favorite foods.