Mash garlic and salt in a mortar and pestle until a paste forms.

Add anchovies, lemon zest, capers, mustard, and pepper to the garlic paste.

Continue mashing until well combined.

Slowly stir in lemon juice.

Drizzle in olive oil in a slow, steady stream while continuing to mash with the pestle until the dressing emulsifies.

Work in the Parmesan cheese until fully incorporated.

Alternatively, puree all ingredients except the oil and cheese in a blender.

Slowly drizzle in the oil while blending until emulsified.

Transfer to a bowl and stir in the cheese.

Refrigerate the dressing in an airtight container for up to 3 days.

Bring to room temperature before serving.