Break the sourdough starter into pieces and place it in a bowl with the water. Stir to dissolve as much as possible.

Add the whole wheat flour and salt, and start mixing with a fork. Gradually drizzle in the extra virgin olive oil and continue kneading, first in the bowl and then on a floured work surface.

Knead vigorously for about 10 minutes, until the dough is smooth and elastic.

Transfer the dough to a bowl, cover well with a kitchen towel, and let it rest at room temperature for 1 hour.

Place the dough in the refrigerator for 24 hours.

After the resting time, remove the dough from the refrigerator and let it sit at room temperature for 2 hours to come to room temperature.

Shape the dough into a round ball, gently flatten it, and roll it out with a rolling pin to about 8 inches (20 cm) in diameter and just under 1/2 inch (1 cm) thick. Let it rise for another 2-3 hours in a turned-off oven with the light on, or in a warm, draft-free place.

Using your fingertips or the handle of a wooden spoon, gently make dimples on the surface of the focaccina. Drizzle with a little extra virgin olive oil and sprinkle with a pinch of coarse salt.

COOKING METHOD 1: Place the focaccina in an air fryer and cook at 355°F (180°C) for 20-25 minutes, until puffed and golden.

COOKING METHOD 2: Bake in a preheated oven at 400°F (200°C), conventional setting, for 20-25 minutes, until the focaccina is puffed and golden.

Serve the focaccina hot, or let it cool completely and fill as desired.