Mix the Manitoba flour and dried beer yeast (or fresh yeast) in a bowl. Add the water and briefly stir with a wooden spoon, add the salt and keep kneading (by hand or with a mixer) until the dough is smooth and uniform.
Let it rise at room temperature for 2 hours.
In the meantime add the grated "Stelvio PDO" cheese, the ham cubes and peas to the Bechamel sauce.
Roll out the dough using a rolling pin and then cut out circles with a diameter of about 12 cm.
Lightly stretch each dough circle by hand, to expand it. Spoon some of the Bechamel sauce filling in the middle, fold the dough over and seal it on the side with your fingers.
Now place the dumplings on a cookie sheet with parchment paper. Mix the tomato sauce with the oregano and spread a little on each dumpling.
Bake the dumplings at 230°C (210°C convection oven) for 18 minutes and let cool before serving.