A simple way to get "more" out of your salt, is to start with BIG crystals, and coat them gently in oil before sprinkling them over the food. That way they do not melt on contact with the food as they are protected from the water by the film of oil , and add a awesome crunchy texture to the serving.
Technically I think that your question is more chemistry related and not directly cooking related.
I can give you a few hints no what you can do to get crystals, but a chemist should be able to give you a lot better advice.
First, making the salt water solution:
- Get distilled or at least demineralized water. You do not want to
add random minerals that are dissolved in water to your salt :)
- Make a saturated solution of salt-water at a high temperature ...
something like 90-95C (~194-203F). The idea is that at higher
temperatures you get more of the salt dissolved in the water more
- Keep the salt solution at that high temperature (well covered to
reduce evaporation) for some time to make sure that any undissolved
salt has settled to the bottom. You are interested only in the salt
in the solution.
- Take only the saltwater without any undissolved salt. Until and
including this step, the solution should be best keep at the same
temperature. If you have to move the solution, at least make sure
that the thing that you are moving it into is not cold.
OK, now it is time to make the crystals:
- Crystals grow. If they grow too fast or are disturbed (thermally
or mechanically) they fall apart and end up being smaller. This is
why when you make ice cream you churn the ice constantly (mechanical
disturbing the formation of possibly ice crystals) or chill it with
liquid nitrogen (thermally shocking the crystals and make them break
apart). What you get are very small crystals if you disturb them.
- Crystals grow when they are "forced out of solution" - that is, when
the concentration of the salt in water is higher than the solubility
of salt in water at that specific conditions. Pressure is one of the
factors, but we will just ignore it completely. The factors that you
can work with are Temperature and concentration (just remove
water from the solution by evaporation)
- To get BIG crystals, you have to let them grow slowly.
- So, what you need to do is to cool the solution very slowly
- Evaporate the water out of solution very slowly (take care not to
get dust in the solution during this procedure :) )
Unfortunately this is all the advice that I can give you now. Be aware that crystals are delicate and you might need a few attempts until you get the desired result. As a fun fact, there exist conditions where you will actually get a BIG salt Cube aka, a single salt Crystal by doing this :) . Cool indeed , but not very useful for cooking :)