Pour a small amount of the salt onto a plate. Make a small slit in the lime half and run the rim of a glass through it. Then, tap the rim of the glass around the salt to coat. Fill with ice and set aside.
Throw the jalapeño slices into a cocktail shaker (amount depends on the level of spice you want) and muddle using medium force. Fill the shaker up halfway with ice. Add the tequila, Cointreau, agave, juice of the 1/2 lime, and a splash of the freshly squeezed orange juice.
Shake vigorously until the shaker becomes frosty. Strain into the salted glass. Garnish with a slice of lime and jalapeño. Enjoy!