Thinly slice the jalapeño, keeping the seeds, and place in a mason jar or other container that can be closed tight. You can use more than one jalapeño if you really want to get spicy!
Pour tequila over the sliced jalapeños
Screw on lid and shake well to introduce the jalapeños and tequila together
Let them get to know each other in a room-temperature dark place, like your kitchen cabinet, for at least 24 hours. I have let them hang out for up to 5 days for some really spicy margaritas! Taste test to determine if it has enough flavor for you, and don’t be alarmed if your tequila begins to take on a greenish hue. It’s just the natural color from the jalapeños.
When it’s ready, pour tequila through a mesh strainer to remove jalapeños and seeds, but DON’T GET RID OF THE JALAPEÑOS!!! They will make a great garnish later. Set them aside.
Pour back into jar or other container that easily closes and pours. Sometimes I pour it back in the empty tequila bottle, and make sure that I label it.