Take a strainer and start to make a layer with the slices of aubergines (4), then sprinkle with salt (5) and continue to make other layers, always alternated with salt. In this way you will expel all the water from the aubergines and the parmigiana will be better. Leave the strainer to drain the water, putting a weight on the aubergines (6), for at least five hours. After this time, squeeze the aubergines with your hands, t have the best Parmigiana.