This came about due to a friend's offhand remark about infusing tequila for a few minutes with a sliced, tiny hot pepper; for a shortcut, just juice it up for a spicy, balanced, and not-too-sweet drink.
1 personal-sized watermelon (no rind, juiced)
1 jalapeño (juiced)
1 lime (juiced)
1 tsp. cane sugar
1 tbsp. agave nectar
pinch of sea salt
Maldon salt for rim
Whisk up the first 6 ingredients and, if you wish, add ice and tequila to the salted glass before pouring in the watermelon mixture.