Romance~purple Sweet Potato Cake Roll
1.
The purple sweet potato is peeled, cut into small pieces, steamed, sugar is added, and the milk is pressed into a puree with a spoon and set aside.
2.
Add a few drops of vinegar to the egg whites and add one third of the sugar when the thick foam is formed. Continue to beat the middle two times and add the remaining sugar until the wet foam is reached (Figure 2).
3.
The egg yolks are whitish with sugar. Add oil and beat well, then add water and stir well.
4.
Take one third of the meringue and add it to the egg yolk paste and mix well.
5.
Pour all into the meringue and stir evenly.
6.
Put greased paper on the baking tray, pour the egg batter, smooth it, and shake it a few times. Put it in the preheated oven and heat it up and down at 170 degrees for 18-20 minutes. .Take out the greased paper, turn over and tear off the bottom greased paper.
7.
Spread the mashed purple potato.
8.
Roll up with oil paper, set for 10 minutes, squeeze the purple potato mash to decorate.