2. Wash all four apples, peel them, core them, cut them into pieces, mash them with a clean multifunctional cooking machine, take them out and put them in a clean big bowl.

3. Take half a lemon, squeeze out the lemon juice and drop it on the apple puree, and stir it evenly with clean chopsticks.

4. Put the clean oil-free and water-free pot on the gas stove and turn on the small fire. The pot is hot, pour in the apple puree. Stir with a clean oil-free spatula until the water content of apple puree gradually decreases. Add sugar and stir quickly until the water is dry. Wipe the apple puree on the pot with a spatula, and it will be ready without dripping water. Turn off the fire and take it out to cool.

5. After the protoplasm is cooled, put it in a glass bottle prepared in advance, tighten the lid of the glass jar, put it in the refrigerator, and keep it while eating.