Slice the jalapeño into 1/4-inch rounds, leaving the seeds intact for maximum heat. Pour the tequila into a pitcher or glass and add the jalapeño slices. Let them steep for 15-30 minutes while you prepare the other components. I always taste a small sip after 15 minutes to check the heat level—if you prefer a milder drink, remove the jalapeños earlier, or strain out the seeds for less intensity.

While the jalapeño infuses, prepare your serving glasses. Mix the salt and chili powder together on a shallow plate or small dish. Rub the cut lime around the outer rim of each glass to create a sticky surface. Dip the rim firmly into the salt and chili powder mixture, rotating to coat evenly. Fill each glass with ice and set aside. I always use Maldon sea salt for its larger crystals—they stay on the rim better and provide a satisfying crunch with each sip.

Add the chilled watermelon cubes, lime juice, and agave nectar to a blender. Blend on high speed until completely smooth, about 1-2 minutes. The watermelon should be pre-chilled to keep the drink cold without diluting it too much with melting ice. Strain the mixture through a fine-mesh sieve if you prefer a completely smooth texture, though the chunky consistency is optional depending on your preference.

Pour the watermelon blended mixture from Step 3 into each prepared glass from Step 2, filling about three-quarters of the way. Carefully pour 2 tablespoons of the jalapeño-infused tequila from Step 1 into each glass and stir gently to combine. Top each drink with a thin lime round from your prepared slices and serve immediately.