IngredientsFlour & grain
Kartoffelstärkepotato starch
Pure starch from the potato, white and fine, with no taste of its own. It is not a flour: no protein, no bran.
It binds earlier and at a lower temperature than corn starch, and it stays clear. That is why it sits in potato dumplings, in fruit tart glaze and in pale sauces that need a shine.
In Mexikoin Mexico
It is called fécula de papa. Ordinary supermarkets rarely stock it; baking supply shops and Mercado Libre do.
Ask for fécula alone and you get fécula de maíz. The word papa has to be in the sentence, or you go home with corn.
Ersatzwhat to use
Corn starch works most of the time. It binds cloudier, wants more heat and leaves a faintly floury taste.
For tart glaze and for dumplings the real potato starch is worth hunting down: there you see and taste the difference.
Vorsichtwatch out
Potato starch breaks fast under heat. Let the bound sauce reach a rolling boil and it thins out again for good.
Stir it into cold liquid, pour it into the hot pot, let it come up once and take it off the fire.