Combine the base ingredients

• Place the egg, lemon juice, Dijon mustard and salt in a tall narrow container or mixing bowl.

Add the oil

• Pour the avocado oil over the egg mixture, letting it settle on top.

Blend the mayonnaise

• Place the immersion blender at the bottom of the container and blend without lifting it until the mixture starts to emulsify.
• Slowly raise the blender head to incorporate the remaining oil until thick and creamy.
• Alternatively, whisk by hand, adding the oil in a thin stream while whisking constantly.

Taste and store

• Taste and adjust the seasoning if needed.
• Transfer to a jar and refrigerate; it will keep for about a week.