How much lecithin in a dressing?

you will have to play around a little but use any where from .01% to 1.0%

For dressings i have found that Xanthan gum works better again only a small amount about .5% of the total weight of your other ingredients.

This is a common mistake that many people make. It’s easy to underestimate the potency of molecular cooking ingredients and end up using too much of something. The best way to get the right amount to use is by following the recommended ratio. In the case of lecithin, the suggested amount is between 0.5% and 1.0% of the liquid weight. Let’s say you are using 250 grams of liquid, you can add 1.25grams to 2.5 grams of lecithin.

It’s always a good idea to add the least possible amount first. After adding the initial amount check out the texture and overall outcome before you add more. It’s always easier to add more when needed, instead of figuring out how to thin down your dressing and get it to the right consistency.