Start boiling the potatoes, peeling and mashing them, same as you would do to prepare mashed potatoes. Let me them cool down to ambient temperature.
In a bowl, start mixing the flours with the yeast. I usually use active dry yeast, but fresh yeast will work the same. In that case, I would use about 10 gr.
Time for the mashed potatoes to come in! Be sure they are not warm, not a good thing for the yeast.
Now add the water. You can add it all at once, it will work anyway! Mix with your hands or with a fork... I usually start with the fork and complete with my hands to work the dough.
No focaccia will be a focaccia without EVO oil. Choose a good one, it is an important ingredient, giving the right texture and taste to your focaccia barese!
When the dough has absorbed the EVO oil, time to add the salt. Always keep on mixing.
You should get to an unfinished dough like the one in the picture. It is still rough, just cover it with a plastic film and let it rest for 15 minutes.
After the first rest, do what we call "fare le pieghe". It's better explained in the video, lol. This will give strength to the gluten network. This will be done twice. The schema is: 15 minuts rest - folding - 15 minutes rest - folding - 15 minutes rest.
After this, take your iron pan and grease it with plentiful EVO oil. Stretch the dough to make it fill the pan and...
... let it rest for 2.5 - 3 hours until it doubles. What you will get is a wonderfully risen dough like this. Isn't it a Beauty? :)
Time to be messy now! Break the cherry tomatoes and put them as a topping. Don't spread all the juices on you, the focaccia needs them!
Now add oregano and salt according to taste (but don't be shy with oregano!), some EVO oil again and eventually fill all the blanks with olives. It's something your children will love doing, if you want. The final result is the focaccia ready for the oven...
... that should be hot (the hotter the better). After a few attempts, my best results have been with 280 °C, for about 30-35 minutes. The final result is something that if you try once... it won't be the last! Buon appetito :)