"You know...just like everyone else does. Egg whites...powdered sugar....done."
I really wasn't trying to brush anyone off or keep some kind of weird icing secret. And it was only later that I found out that most people use a meringue powder to make royal icing. But it's still basically the same way.
Dried Egg White Royal Icing
4 tsp dried egg whites
1/4 c room temperature water
1 tsp lemon juice (or 1/4 tsp cream of tartar) *** BOTH ARE OPTIONAL
3 c powdered sugar
~~OR, for a larger batch ~~
1/4 cup dried egg whites
3/4 cup room temperature water
1 Tbsp lemon juice (or 1/2 tsp cream of tartar) *** BOTH ARE OPTIONAL
2 pounds powdered sugar
Mix water and egg whites in the bottom of a mixing bowl. Let stand 3-5 minutes. Add lemon juice or cream of tartar if you choose. Beat on high speed until stiff peaks form. Add powdered sugar one cup at a time and mix on medium just until combined. The resulting icing should also be about stiff peak thick. (Because I like it that way. If you don't like to make it stiff first, then don't add all the powdered sugar.) I usually wait until after I color my icing before I thin it down. But...you know....do what you want.