Location in the valley: Solenzara (Sari). Park at the Belvédère de la Penna viewpoint 400 m away, in the village of Sari Solenzara (in front of the orientation table).
(S/E) We go back about 50 m along the road and turn left onto a winding road that goes uphill. There we pass an old oven on the right.
(1) After about 3 minutes, turn left at the fork and follow the cement path uphill (note: the path is rocky at the end).
(2) After a good 10 minutes, we arrive at a crossroads near a reservoir.
(3) Behind this reservoir, an orange-marked trail climbs towards Monte Santu, heading south-west.
(4) After about 30 minutes, the trail splits (sign): take the right fork and you will come directly to the summit of Monte Santu, which is covered in scrub (the left fork leads to a south-facing rock face).
The descent follows the same route in reverse to the viewpoint (S/E).

and then there's the mask... and in the Corsican maquis... useful?