Prep the Glass: Rub a fresh lime wedge along the rim of a rocks glass. Dip the wet rim into a plate filled with coarse salt or Tajín until evenly coated. Fill the glass with fresh ice and set aside.
Muddle the Heat: Place 2 to 3 fresh jalapeño slices at the bottom of a cocktail shaker. Gently press them using a muddler to release the natural spicy oils and juices.
Pour the Liquids: Add 60ml of blanco tequila, 30ml of fresh lime juice, and 15ml of agave nectar directly into the shaker over the muddled jalapeños.
Shake Vigorously: Fill the cocktail shaker to the top with ice. Close the lid tightly and shake vigorously for a full 15 seconds until the shaker exterior feels freezing cold.
Strain and Serve: Double strain the mixture through a fine-mesh strainer into your prepared, salt-rimmed glass over fresh ice to prevent floating seeds.
Garnish: Top your perfect drink with a fresh jalapeño coin and a floating lime wheel. Serve immediately!