Fill your higball glass to the top with ice.
Measure 2 oz of tequila using your jigger and pour that over the ice in your glass.
Meausre 4 oz of soda water using your jigger and pour that over the ice in your glass.
Use you bar spoon to gently, but completely mix the tequila and soda together.
Add a lime wedge by cutting a lime into slices and then cutting a notch in the pulp of one slice. Place the lime wedge on the rim of your glass.