Remove the arugula from the stalks and wash thoroughly, pat dry or spin. Wash and core the chilli pepper. Peel and split the garlic.
Put all ingredients in a tall container and puree with the blender. Season to taste with salt.
Keeps in a clean glass and covered with cling film or screw cap for 6-8 weeks in the refrigerator. It is important that the surface is always covered with oil.
You can use the pesto as a spread, with pasta and as a dip for vegetables, meat, cheese and crackers, chips, etc.