In a medium, nonreactive bowl, combine the warm water and mashed potatoes. Mix well with a whisk or fork until combined well.
Add flour, salt, honey, 1 tablespoon of olive oil, and the leaven. Stir with a fork, dough whisk or your clean hand until you have a consistent dough. It will be very wet and very shaggy. Cover the bowl with a thin cloth or plate. Note the time. This is the beginning of the bulk fermentation, which will last approximately 3½ to 4 hours, depending on the temperature in your kitchen.
After 30 minutes, do the first set of stretches and folds of the dough. With a wet hand, reach underneath the bottom of the dough, pull the dough up, and fold it over onto itself. Turn the bowl a quarter turn and repeat the stretching and folding. Repeat two more times, for a total of four turns.
Repeat this four-turn stretching and folding about once an hour during the bulk fermentation. By the end of the bulk fermentation, the dough will be smooth, glossy, elastic, and filled with air.