1/3 cup sugar
3 cups tequila blanco
1 1/2 cups fresh lemon juice
1 1/4 cups fresh lime juice
1/2 cup triple sec
1 jalapeño, halved lengthwise
Bring sugar and 1/3 cup of water to a boil in a saucepan, stirring to dissolve sugar. Let simple syrup cool.
Combine simple syrup, tequila blanco, fresh lemon juice, fresh lime juice, triple sec, and jalapeño, in a pitcher.
Chill for at least 30 minutes or up to 3 hours (taste every 1/2 hour or so until spiced to your liking); remove jalapeño.
Rub a lime wedge over half the rim of highball or rocks glasses; dip into kosher salt.
Serve Margaritas over ice in prepared glasses; garnish with sliced cucumber and jalapeño.