Place two serrano chiles inside a bottle of tequila for 2 days. Gently shake daily.
After two days remove the serrano chiles, refrigerate, and reserve.
Inside a martini shaker squeeze all citrus juices, 1 ounce infused tequila, simple syrup, and ice. Shake and pour into a salt-rimmed glass, including the ice. Garnish with orange, lemon, and or lime wedges.
For added spice, slice the serrano chiles and add 2-3 thin slices in the margarita.