Put the tequila, Cointreau, fresh lime juice, lime zest, diced frozen cucumber, 4 fresh jalapeño slices, agave nectar and ice in the blender and blend until smooth and creamy.
Place 1-2 tbsp of salt on a small plate. Run one of your discarded lime halves around the rim of each glass to lightly coat with juice. Dip the rim of the glass into the salt plate to lightly rim the glass.
Pour the contents of blender into each glass and garnish each glass with a slice of jalapeño, lime and cucumber. Serve immediately.
If your margaritas are too thick add 1 tbsp of lime juice at a time with the blender running until you achieve desired consistency.