Gather all your ingredients on the kitchen counter for a seamless process.
In a tall container, add 1 egg, 1 tablespoon of fresh lemon juice, 1 teaspoon yellow mustard, and 1/2 teaspoon salt.
Slowly pour in 1 cup of avocado oil while keeping the blender off.
If using an immersion blender, submerge it and turn it on, pulling it up as the mayo emulsifies. If using a regular blender, blend on low, gradually increasing speed.
Taste the mayo and adjust the salt or lemon juice to your liking.
Transfer the mayo into a storage container, seal it tightly, and store it in the refrigerator.
