Gather all ingredients.
Using a Y-peeler, remove yellow zest from lemons in large strips, avoiding the bitter white pith as much as possible. This should yield about 1/2 cup zest. Juice lemons to yield 1/4 cup juice. Discard juiced, skinned lemons; reserve any unjuiced lemons for another use.
Place lemon zest, lemon juice, Parmesan, almonds, water, garlic, salt, sugar, pepper, and 3 tablespoons oil in the jar of a blender; process until lemon zest is finely chopped and mixture is roughly combined, about 15 seconds, stopping to scrape down sides as needed.
With blender running, slowly pour remaining 3 tablespoons oil through food chute, processing until mostly smooth and emulsified, about 1 minute, stopping to scrape down sides as needed.
Use immediately or store in an airtight container for up to 1 week. This recipe was developed by Tricia Manzanero Stuedeman
