In a medium bowl, add the bread flour, all purpose flour, flaxseed, salt, and dissolved yeast and briefly stir to combine, with a wooden spoon. Pour in the warm water and continue to stir. (Alternatively, you could make in an electric mixer and use a dough hook, on low speed).
When a soft sticky dough begins to form, transfer to a clean work surface. There will be some excess flour and dry dough crumbles - you will be able to blend this in as you knead.
Knead well with the heel of your palm for about 8-10 minutes or until it can be formed into a smooth ball. The dough should be elastic and stretch as you pull it apart but not easily break.
When you can shape the dough into a ball, transfer it to a clean bowl and coat with a thin layer of extra virgin olive oil. Cover the bowl with plastic wrap and place a dishtowel on top. Find a warm, dark place to let it rise and leave ir for 8 hours until the dough doubles in size.
Once the dough rises and doubles in size (about 8 hours), remove the dough from the bowl. Punch it down to its original size and divide it in half. Use immediately or store in the refrigerator or freezer for later use.