For numerous reasons, I need to prepare the vast majority of food salt-free. Been doing this since the 80's, and now we are very sensitive to any added salt in our food. This extends to, for instance, salting the water for boiling pasta or vegetables.
When I read about using a Mortar and Pestle, recipes often suggest adding a little salt to act as an abrasive. Clearly, from my family's point of view, that salt would not be desirable in the prepared dish.
What can I use as an alternative, without changing the flavors too much. For example, sugar might work from the abrasive point of view, but would add sweetness where it wasn't expected.
(Irrelevant, but someone will probably ask. 1/2tsp of salt in a meal is enough to cause my partner to be very ill. Hence the salt-free regime.)