I saw Cooper27 thinking of making mayonnaise, and thought to repeat a simple technique I shared over on LCHF.
Use a light olive oil or avocado oil to really get the benefit of making it yourself.
Just in case anyone is unaware of the power of a hand blender to make mayonnaise, its amazing. I used to make it in the food processor, but that took a bit of time and made a bit of mess. With the stick/immersion/hand blender, I just break a whole egg into an empty Douwe Egberts coffee jar, salt, pepper, mustard powder, splash of vinegar and glugs&glugs of oil. Stick in the blender, press the button and a few seconds later I have half a jar of mayo. Lid on the jar and into the fridge, and rinse off the blender.
(not my video)