1. Preheat the oven to 400 degrees F (200 degrees C). Prick each potato a few times with a fork and place on a baking sheet.

2. Bake potatoes in the preheated oven until tender when pierced with a knife, about 50 minutes. Cool until easily handled, about 10 minutes.

3. Peel potatoes and pass through a ricer or food mill into a large bowl. Make a well in the center and pour in egg; mix well.

4. Whisk potato starch, sweet rice flour, and salt together in a bowl. Sprinkle over potato mixture; stir until a soft dough has formed. Cut dough into 4 equal parts with a knife or pastry cutter.

5. Dust the work surface with rice flour to keep dough from sticking. Roll out 1 piece of dough into a rope about 1 inch in diameter. Cut into 1-inch gnocchi. Gently roll each one with the back of a fork to create ridges. Repeat with remaining dough.

6. Shake off any excess rice flour and let gnocchi rest, about 5 minutes.

7. Bring a large pot of salted water to a boil. Add gnocchi in batches and cook, without stirring, until they float to the top, 1 to 2 minutes. Remove with a slotted spoon.

Tips

Substitute arrowroot flour for the sweet rice flour if desired.

If not cooking right away, roll the gnocchi in rice flour and arrange on a baking sheet about 1/4 inch apart. Let rest, about 5 minutes. Refrigerate for up to 24 hours or freeze up to 6 months. (Once cooled or frozen, the gnocchi won't stick together so you can transfer them from the baking sheet to freezer bags.)

Frozen gnocchi will take about 3 minutes to cook. Thawed, they can be added directly to your favorite sauce that has already been heated. The texture of cooled or frozen gnocchi may differ from fresh.