Add the jalapeño slices and sugar to a jar. Pour the boiling water on top and then stir. Let sit for 15 minutes. Remove jalapeño slices and let the syrup cool before using.
For the Margarita
Add all ingredients for the margarita to a blender jar and blend.
To rim the glass, swipe some of the simple syrup on the rim of the glass. Add Tajin to a plate and roll the wet part of the glass in it to coat the glass.
Pour the margarita mix into the glasses and garnish with a twist of lime and a few jalapeño slices.
Video
Notes
Store leftover simple syrup in the fridge for 2-4 weeks. If it looks or smells off, toss it.Make margaritas as you want them.If you don't have Tajin, use equal parts chili powder and salt.