Take double rocks glass and run a lime wedge around the rim of the glass
Dip upside down into a small bowl of Tajin, you can use salt if that is what you prefer
In small tin add agave and 2-3 pieces of roasted jalapeño
Muddle jalapeños into the agave
Also in small tin add tequila, fresh watermelon juice, and fresh lime juice
In large tin add ice
Combine tins, form a seal, and shake vigorously for about 15 seconds
Add fresh ice into your glassware
Break seal on tins, and strain cocktail over that fresh ice
Garnish with a Lime wheel and sprinkle left over discs of roasted jalapeño on top of cocktail
Enjoy!!