Whip the egg whites with the cream of tartar until frothy and pale, adding in the sugar in bit at a time until the whites are whipped into a glossy thick meringue that holds a peak. Be careful not to over whip.
Take 1/3 of the whipped egg whites and whisk it into the bowl with the yolks until completely incorporated. Add half of the remaining whites and whisk into the yolk batter, being careful not to deflate. Transfer the egg yolk mixture to the remaining egg whites, whisk and then use a spatula to fold together.Heat up a large non stick frying (with a lid) pan over low heat. Very lightly brush with oil and use a paper towel to rub it around. You want a very light film. Using an ice cream scoop or measuring cup, scoop the batter onto the pan. Unless you have a very large pan with a lid, it’s probably best to make these two or even one to a pan. Scoop the batter onto the pan, cover and cook for 4-5 minutes. If you have a crepe maker or griddle with a lid that will cover the entire thing without touching the pancakes, use that on the lowest setting.