The trick is to add it very slowly in just a drizzle.
I got an used salad dressing plastic container with the small hole in the top, then cut a square out of a Ziploc and put it over the top of the container, screwed the lid on top of that, and then got a tooth pick and poked a small hole through the small hole in the squeeze lid.
(This sounds so complicated-I just rigged up a small squeeze bottle)
It helps if someone else drizzles while you whisk, or beat.
It will not set up in the refrigerator, but you can use it to cook with. Stir fry, or anything that the sour from the vinegar won't be alarming in.