Add the cilantro, garlic, cashew nuts, lemon juice and shredded parmesan cheese to a food processor. Pulse a few times until coarsely chopped.
With the processor running, slowly drizzle in the avocado oil until the mixture is smooth and well blended. You can adjust the amount of oil to achieve your desired consistency.
Taste the pesto and season with salt and pepper.
Use immediately as a sauce or condiment over pasta, grilled meats, or vegetables, or store in an airtight container in the refrigerator for up to 5 days.