What preparation or structural change to potatoes is most effective for significantly lowering their Glycemic Index (GI) score?

Boiling them until just tender or subsequently cooling them after cooking

The Glycemic Index (GI) of a potato is highly variable, heavily influenced by how it is prepared and consumed. Methods involving high heat and short cooking times, such as deep-frying or baking until very soft, tend to yield a higher GI score, which can cause a rapid spike in blood sugar. Conversely, methods that allow starches to stabilize result in a lower GI. Specifically, boiling the potato until it is just tender, rather than overcooked, or crucially, subsequently cooling the cooked potato, can significantly mitigate this effect. This cooling process fosters the conversion of starches into resistant starch, which, by resisting digestion in the small intestine, reduces the sharp rise in blood sugar typically associated with starchy foods.