For the basic dough: Sieve flour onto a clean work surface and make a deep well in the center. Crack in the eggs and use a fork to gradually work them into the flour to form a shaggy dough. Then continue kneading with your hands until the dough can be formed into a ball. Continue kneading for approx. 10 min., or until the dough is soft and elastic. Cover with an upside-down bowl and let rise for 30 min. If the dough is too dry or too sticky, adjust the consistency with water or flour.
For the red pasta: Mix beetroot with eggs in a blender until smooth. Sieve flour and semolina onto a clean work surface and make a deep well in the center. Then add the beetroot purée and work into the flour with a fork to form a sticky dough. Continue kneading and proceed as with the basic dough.
For the green dough: Blanch spinach for 1 - 2 sec. in boiling water and then rinse with ice water. Drain through a sieve and use a kitchen towel to squeeze out excess water. Mix spinach with eggs, then proceed as with the other two doughs.