Soak the cashew nuts in boiling water, just enough to cover the nuts and allow to soften for at least 30 minutes.
Wash the red peppers and place them whole in the air fryer at 200°C (390°F) for 20 minutes, flipping half way through (alternatively you can cook them in a preheated oven at the same temperature for 30-35 minutes or on a hot grill pan until skin is charred).
Remove the peppers from the air fryer basket and allow to cool them to the touch.
Drain the cashews and place them in a blender bowl.
Remove the skin and seeds from the peppers and add their pulp to the blender bowl.
Add all the remaining ingredients and pulse until everything is combined and the pesto has reached your desired consistency.
Use the vegan grilled pepper pesto to coat pasta, as a dipping sauce, bruschetta topping or to enrich your favourite dishes.