Grate 2 limes onto a baking sheet lined with parchment paper. Set the oven on its lowest setting for a couple of hours. OR, I put it in the oven after I’ve been cooking. I turn of the oven, because it stays warm long after its been turned off. You can leave it to “dehydrate” overnight.
When it has finished dehydrating (we’ll have a finished version). Place 4 tsp in a food processor with 2 tsp of red chili flakes. Pulse once or twice, so that flakes have broken into a fine powder. Add 1 cup of salt. Pulse once or twice to combine (careful that you don’t break up the salt).
Pour into a container that has a sealed lid. Leave overnight in a dry spot without the lid on to make sure the mixture is super-dry. I leave mine on top of my stove.
Place tight fitting lid on top and store somewhere dry. You salt will last up to one year.