Make the Habanero Simple Syrup

1. In a small saucepan, combine the sugar and water over medium heat. Stir gently until the sugar dissolves completely and the liquid turns clear, about 2 minutes.
2. Add the sliced habanero peppers, reduce the heat to low, and let them steep for about 10 minutes. The syrup will take on a faintly golden tint and smell warm, floral, and slightly fruity. For more heat, steep up to 20 minutes. Taste carefully with a small spoon — it should have a slow, pleasant burn that builds at the back of your throat.
3. Strain out the habanero slices through a fine mesh strainer and let the syrup cool to room temperature. Transfer to an airtight container and refrigerate for up to two weeks.

Make the Fresh Watermelon Juice

1. Cut the watermelon into large chunks, discarding the rind. Add the chunks to a blender and blend until completely smooth and liquid, about 30 seconds.
2. Set a fine mesh strainer over a large bowl or pitcher. Pour the blended watermelon through, pressing gently with a spatula to extract as much bright pink juice as possible. Discard the pulp and seeds. Refrigerate the juice until cold and ready to use.

Shake and Serve

1. If rimming the glass, run a lime wedge around the rim of a rocks glass and dip it into a plate of kosher salt, rotating to coat evenly. Fill the glass with fresh ice and set it aside.
2. In a cocktail shaker, combine the blanco tequila, Cointreau, habanero simple syrup, fresh lime juice, and fresh watermelon juice. Fill the shaker with ice, seal it tightly, and shake vigorously for about 15 seconds until the outside of the shaker feels ice cold and frosty to the touch.
3. Strain the margarita into the prepared glass over fresh ice. The color should be a gorgeous coral pink. Garnish with a lime wedge on the rim and serve immediately while it is perfectly cold.