Fill 450 ml lukewarm water into a jar and add the yeast. Stir briefly to dissolve the yeast in the water. Set aside.
In a bowl add all the dry ingredients. Then add the oil, the vinegar and yeast-water-mixture. Now stir all with a wooden spoon or if you prefer with a kitchen machine. All ingredients should be very well combined.
Place a towel over the bowl and leave it for 40 minutes in a warm place, so the dough can rise.
Meanwhile fill the kitchen sink with lukewarm water and immerge the two pieces of the clay pot into the water. Let it soak for the time the bread dough rises.
After the 40 minutes get the bread dough out of the bowl on the kitchen counter and with enough additional flour of your choice knead the dough again for a minute or two. Don't get a plain surface, just let enough folds on the top. The bread looks much better this way as they will open during the baking.
Place the bread loaf in the clay pot, lit on the top, and in the COLD oven. Now switch on 240°C/460°F and let the bread bake for around 80 to 90 minutes.
Take the clay pot out of the oven, place the lid back in the open oven and take the bread out of the pot. Be careful, pot and bread are super hot. Knock on bread's bottom (not on heaven's door). If the sound is hollow the bread can be placed on a cooling rack for at least 5-6 hours.
Instead of millet flour I tried also Teff flour. Comes out great as well.
You can slice the bread and freeze the slices. They are great right away or toasted.