How do I reduce the starch in peeled potatoes?

The short answer is you can’t. Starch, the nutrient-rich carbohydrates within is what makes a potato well, a potato. What you can do however, is (once peeled) cut the potato to your preparation slices, chunks, etc. to expose some of the starch on the potato’s cut, surface. Then, soak and rinse the raw pieces with clean water several times, until the water within is clear.