Why make your own? I make it to control what I consume, I know what's in mine when I make it myself. I don't want to eat soybean oil as all highly refined oils are high in Omega 6 fatty acids (they're inflammatory).
The problems with homemade mayo? Normally it ages too fast and needs to be used up within a week. The following recipe has a tweak that keeps it good for at least a month.
The original recipe is here, and also my changes because I can't not change a recipe. Frankly I couldn't pour off enough yogurt whey to get the required amount. Recipe with my notes follows.
Homemade Mayonnaise that Lasts Longer
A standard mayonnaise recipe with 1 tablespoon of whey added--instead of a week in the refrigerator, your homemade mayonnaise will keep for a month.
Ingredients
1 egg + 1 egg yolk (room temperature)
2 teaspoons apple cider or white vinegar
1 teaspoon Dijon mustard
1 tablespoon whey (drained from plain yogurt) (I just use plain yogurt with no draining. Could lemon yogurt be used? Might be worth a try but it will probably be sweetened.)
Pinch of sea salt
1 cup avocado oil (instead, any combination of the following [pick 2]: 50/50 coconut oil or MCT oil or buttery EVOO [pecan oil might be good])
Dash of cayenne (red pepper)
Instructions
Combine first five ingredients in a food processor bowl, a blender, or a medium mixing bowl. Blend well. (I use an immersion blender and a beaker.)
Drip or barely trickle 1 cup of avocado oil into egg mixture with machine on or while you whisk vigorously by hand.
Add a dash of cayenne.
Pour finished mayonnaise into a glass jar and cover. Allow to sit on the kitchen cabinet at room temperature for 8 hours, then refrigerate.
Notes
This mayonnaise will stay fresh for about a month when refrigerated and it’s delicious.
One of the reasons I like to make my own mayonnaise is so I can use one of my favorite foods, avocado oil. You can substitute vegetable oil or grapeseed oil. I don't personally care for olive oil in my mayonnaise. Namely, because the flavor is too strong. (Wrong olive oil then. Use a lesser grade, not EVOO, or use an olive oil from ripe olives. I use California brand “blended” olive oil from a bunch of different countries and 50% MCT oil and the mayo is delicious. I have used high grade EVOO in the past, and yes it does impart a distinctive flavor. Try different oils and see if any give a unique taste that you like!)