I second that stick blender idea. So easy!
Get a mug that the blender fits in with maybe 1/4 inch to spare.
Dump in an egg, 1/3 to 1/2 full with oil.
Stick blend! Takes a few minutes but let it fully blend. Start with the blender resting on the mug bottom until it takes.
Then add some mustard, vinegar whatever and blend that in. So good.
Protip: Don’t use flaxseed oil.
I use the flask that my immersion blender came with but the idea of using a jar with a lid has occurred to me as it is then ready to pop in the fridge.
@MelTar had this recipe for duck fat in another thread and after reading this one, I’m determined to try my own mayo now. And I never really liked mayo before Keto! I also want to try this with bacon juice. I think it’d be a grand slam!
1/2 cup duck fat, slightly above room temp
4 large egg yolks
1 1/2 T dusseldorf or dijon mustard
Juice of one lemon
Salt and pepper to taste
Blend all the ingredients except the duck fat. Then slowly drizzle the duck fat into the egg mixture while blending. Viola! Duckinnaise.
I use my immersion blender and the tall measuring cup that comes with it. You can also use a regular blender or a food processor. (Or a whisk if you have forearms like Popeye). You don’t want to overwhip the egg yolk mixture but blend it enough so that the ingredients are thoroughly disbursed and the mixture is smooth. That’s when you start drizzling in the the duck fat.
Ooh! Would need to find one that fits properly, but that’s an excellent idea!
I use wide mouthed 750 ml mason jars - they have straight side without shoulders, great for all kinds of creamy sauces, easy to clean.
https://www.amazon.ca/gp/aw/d/B01C4K80B4/ref=yo_ii_img?ie=UTF8&psc=1
To add another opinion to the list, I love this stuff (chosen foods) more than normal mayo. 
Also if you don’t have a costco with it near you they do sell a 3pack (or at least they used to) on their website for a much discounted price. I got lucky that we had been eating this stuff for awhile and then my costco picked it up 
It is true that seed oils are said to be too high in poly unsaturated and mono unsaturated fats (love the graph!) and yet, Phinney and Volek recommend canola oil. That really puzzles me.
I think “The Art and Science of Low Carbohydrate Living” came out in 2011. The advise to eliminate canola oil may be a more recent revision to Keto guidelines based on new information.
That’s what I thought until I saw that Virta’s website recommends canola oil! I was shocked. Between that recommendation and Phinney’s attack against fasting, I have to say that he isn’t someone I trust anymore.
I agree with you! And it is very expensive! Yuck
Next time I will just make my own Mayo with organic eggs and olive oil, plus lemon and sea salt, and some mustard! Nothing compares to that, and it is quick in the food processor
