Focaccia with "indiretta" leavening

The “indiretta” leavening or “Biga” it’s a technique that consists in the preparation of two doughs. The first one, Biga, will develop the yeasts and become a key ingredient of the final dough. Here’s a recipe by by Piergiorgio Giorilli in collaboration with Molino Grassi.
Preparation for 4-6 tins.
Biga
180 g Flour 00 Lievito Molino Grassi
80 g Water (45%)
1.8 g Yeast (1%)
Times for the biga dough
Spiral mixer: 4 minutes on the first speed
Plunging mixer: 4 minutes on the first speed
Fork mixer: 5 minutes on the first speed
Temperature for the leavening of the biga: 17°/20°C
Final dough
Biga
600 g Flour 00 Mediterraneo Molino Grassi
350 g Water
50 g Extra-virgin olive oil
15 g Yeast
15 g Salt
10 g Malt
Time for the dough
Spiral mixer: 6 minutes on the first speed – 4 minutes on the second speed
Plunging mixer: 7 minutes on the first speed – 5 minutes on the second speed
Final temperature of the dough: 25°/26° C
For the brine
50 g Hot water
50 g Olive oil
20 g Salt
 
Procedure. Knead together all of the ingredients apart from the salt which is to be added halfway through. Let it rest at room temperature for about 20 minutes. Lay the pieces out on the pre-oiled trays and place in the fermentation cell at 28 °C for about 30 minutes. Distribute the brine equally over the pieces of dough then with your finger make deep holes in the dough. Place it back into the fermentation cell at 28 °C for about one hour. Bake in a steam oven at 240 °C.