• Using a mortar and pestle, grind the chillies into the salt until the salt is slightly pink and there are no longer any large chunks of the chilli peppers.
• If you don't have a mortar and pestle, use a heavy-duty freezer bag instead. Put the salt and chilli in the bag and use a rolling pin to crush the chilli in the salt until its evenly distributed. You could also use the rolling pin directly on the salt and chillies on a hard surface like a cutting board, but then your rolling pin would have chilli oil on it and that might result in some spicy pie crust later on.
• Store chilli salt in an airtight container.

To assemble the amuse bouche:

• Cut watermelon into 1x2 inch slabs, about 1/2 inch thick. Sprinkle with a pinch of chilli salt, black pepper, and a couple pieces of chopped scallion.
• Serve immediately as a fun little appetizer and palate cleanser!