Sweet and Fragrant Blueberry Rolls
1.
Egg yolk paste: pot + water + powdered sugar (mixed and melted) + oil + sieved low powder + corn starch + egg yolk → mix evenly on the left and right sides.
2.
Egg white paste: egg white + salt + cream of tartar (not available) → medium-low to coarse foam in the whisk (pictured).
3.
Follow the previous step + sugar (additionally) + vinegar → whisk from mid-range to high-end until it is hard to beat (as shown in the picture).
4.
Take 1/3 of the egg whites into the egg yolk paste, mix well from the outside to the middle, and then put all the egg yolk paste into the egg white paste and mix well. Spread greased paper on the baking tray, pour the cake batter, smooth it, and put it in the middle layer of the preheated oven at 150 degrees for about 20 minutes.
5.
Lay the baked cake slices flat, spread some blueberry sauce in the middle,
6.
After rolling up, cut into appropriate size.