Toast the cashews in the air fryer: Preheat the air fryer to 325°F (163°C).
Spread the cashews in a single layer in the basket. Air fry for 5–7 minutes, shaking halfway, until lightly golden and fragrant. Let them cool for 5 minutes.
Soak the cashews: Place the toasted cashews in a bowl and cover with hot water.
Soak for 20–30 minutes to soften. For a faster method, simmer them on the stove for 10 minutes, then drain.
Drain and prep: Drain the cashews well. Save 3/4 cup fresh water for blending.
You can adjust later for thickness.
Blend until creamy: Add cashews, 1/2 cup water, lemon juice, garlic, nutritional yeast (if using), olive oil, salt, and pepper to a high-speed blender. Blend on high for 45–90 seconds until completely smooth. Scrape the sides as needed.
Adjust texture and seasoning: If it’s too thick, add water 1 tablespoon at a time until you reach your preferred consistency.
Taste and adjust salt, lemon, and pepper. Add onion powder or red pepper flakes if you like.
Warm if desired: For a warm sauce, pour into a small saucepan and heat on low for 2–3 minutes, stirring often. Do not boil—just warm through.
Serve: Toss with pasta, spoon over bowls and tacos, drizzle on roasted vegetables, or use as a dip for fries and crudités.