Mix the dry ingredients in a large bowl. Combine the wet ingredients in a smaller bowl. Make a well in the dry ingredients, add the wet mixture and start incorporating the flour in the wet mixture with a spatula until you have a dough.
Take the dough out on a working surface powdered with some cassava or sorghum flour, and gently knead it with your hands until you get a soft texture dough that holds together.
Portion the dough into two equal parts and roll each of them with the palm of your hands in the shape of a cigar. Put the two cigars on the baking sheet and flatten them out. The size will be about 8 inches x 4.5 inches (20 cm x 11.5 cm).
They are now ready for the first bake for 25 mins at 350F/170C in a preheated oven. After the first bake, take the baking sheet out and let the dough cool for about 15-20 minutes, and turn the oven down to 300F/150C.
Gently transfer the logs to the cutting board. Slice them at an angle (about 1/2 inch or more thickness). This is the sensitive step of the whole process. You need a sharp knife (don't use a serrated knife), and you must do it slowly and gently.
Put the sliced biscotti back on the same baking sheet and bake them again, at 300F, for 10-20 minutes. Take them out half-time and turn them on the other side. They are ready when they look and feel dry.
Once they are ready, let them cool and store them in an air-tight glass or cookie jar in the refrigerator. I love to make a few batches and freeze them; they last for up to 3 months and thaw quickly.