Muddle cilantro and jalapeño in cocktail shaker with a little bit of crushed ice.
Add tequila, cucumber juice, Cointreau, lime juice, agave syrup with ice and shake well.
Strain into rocks glass with ice.
Garnish with cilantro, jalapeño or cucumber slice as desired.
*To make cucumber juice, just peel a couple cucumbers and puree them in a blender or food processor. Then strain over wire mesh strainer and toss out the solids. Store whatever juice you don’t use in the refrigerator, it will keep for several days.