Wash seeds.
Drain and place them in a dry skillet and stir until all water is evaporated. Then remove.
Dry-roast salt in a frying pan for a minute over a medium heat, stirring constantly.
Grind fine in a suribachi.
Dry-roast the damp seeds, stirring constantly with a rice paddle or wooden spoon, until most of the moisture evaporates and they begin to pop.
Place the roasted seeds in a suribachi and grind them along with the ground salt. Grind slowly in a circular motion until 80 % of the seeds are crushed.