90 g (30% of the weight of the sweet potato + apple)
1/2 cup plus (100 ml)
Peel the sweet potato thickly, cut into quarters and slice about 5 mm thick. Slice the apple in the same way.
Soak the sweet potato in water for a while to eliminate the bitterness. Put the apple slices in a pan in the meantime, and sprinkle with half the amount of granulated sugar.
After a while, when the sugar has melted, add the drained sweet potato and the rest of the granulated sugar, lemon juice and water, and simmer over low heat.
Skim off any scum, and simmer until the sweet potato is tender. Stir frequently so that the pot doesn't burn.
When the sweet potato is tender, mash it up with a rubber spatula or a pestle. Cook to evaporate the moisture until the mixture is thick and creamy.
Story Behind this Recipe
I make a batch of jam pretty often. I was inspired by a certain bakery chain's "apple potato pies." I was going to make sweet potato and apple jam, but when it was done it was more like cream than jam. But that makes it easier to use, so I uploaded the recipe.
If the water boils off before the sweet potato is cooked through, add some water. There are equal amounts of apple and sweet potato, but change the ratio to taste. Try the cream spread on toast, mixed into pound cake batters and so on. Enjoy it in various ways!