Peel the sweet potato, slice into 1 cm and soak in water. Peel the apple and slice thinly. Put both in a pot and add enough water to cover plus sugar, and a few drops of lemon juice if you have it. Heat on medium (see the Helpful Hints).
Once it's cooked enough so that the sweet potato falls apart and the moisture has reduced by 1/3, stop the heat, add butter, and mix.
Transfer to a plate and it's complete! Eat as-is, or sprinkle cinnamon. Also delicious while cold.
Story Behind this Recipe
I had plenty of sweet potatoes and apples and I wanted to use them up. I remembered this dish that my mother made from long ago, but adjusted it to my liking.
When making this for a weaning child, don't add sugar or lemon, and mince the apple into small pieces. In Step 2, heat until through until the sweet potato starts to crumble, but you can boil until it completely crumbles. Please adjust the sugar amount as desired. For the amounts, I made these amounts for you to enjoy the taste of the sweet potato and the apple. If you increase the amount of sugar, you could use this as a filling in sweet potato pie. This can be frozen as well, so I always make a lot. But my kids always eat it up before I can freeze it.