Combine the three ingredients together in a shallow dish. Mix to blend thoroughly.
Run a small slice of lime over the rim of each glass. Dip the rims into the salt/ancho chili/sugar mix to coat them entirely. Fill the glasses halfway with ice, and set aside.
for the spicy serrano margaritas ::
Add the serrano slice and simple syrup to a cocktail shaker, and muddle together.
Add the strained citrus juices, tequila, and a little pinch of kosher salt to the shaker. Fill the shaker with ice, and secure the lid. Shake vigorously for 30 seconds, then strain into the rimmed glasses.
Garnish with a small grapefruit or lime wedge, and serve immediately.
Notes
The photos have two serrano slices as garnish ... this is an option, but the peppers will directly touch your lips as you drink, and they can be very spicy. I recommend a small slice of lime or grapefruit for garnish instead!FOR SIMPLE SYRUP: (2 different versions, same results:)
Combine 1/2 cup each of HOT water and sugar into a glass jar, seal with a lid, and shake to combine.
Combine 1/2 cup each of water and sugar in a small saucepan over medium heat, and stir until the sugar is dissolved into the water.