Preheat kitchen oven to 160 degrees. Spread out baking sheets with parchment paper.
Mix oat flour and flakes, baking powder, salt and sugar in a large wide bowl. Pork lard and warm water in the center mold.
Prepare into a firm dough . Press into a flat square on a surface sprinkled with oatmeal.
Roll out the dough to a square 3 mm thick, sprinkle with oatmeal if necessary. Cut into 6 cm long lozenges. Repeat the process with the rest of the dough.
Place the oatmeal cookies on the baking sheets, spacing them a tiny bit 5 mm apart, and bake for 25 min. Cool on the baking sheet.