I haven’t tried to make these, but if I ever come across sago flour, I will. They are Brazilian cookies of Portuguese origin, said to have a texture between a macaroon and a meringue.
You might be able to substitute tapioca flour for the sago flour.
5 egg yolks
1-1/4 C sugar
1-1/2 C fine sago flour
Preheat oven to about 250 F. In a mixing bowl, beat the egg yolks until they are thick and light-colored and form ribbons. Then mix in the sugar.
Add the flour a little at a time, mixing well with a spoon at first, and then with your hands. Make the dough thick enough that you can use your hands to form balls, about an inch and a half or so in diameter.
Put the balls on a baking sheet and place in the oven. Leave them for a couple of hours, until they are thoroughly dried out.