Pour the lime juice, tequila, Triple Sec and simple syrup into a pitcher and stir until combined.
Pour sugar onto a small plate. Run a piece of lime all around the edge of the glasses to get them a little wet, and then turn them over and twist them in the sugar until it covers the rim.
Fill up the glasses with ice, and then fill each one half full of the tequila lime mixture. Now pour in the proscecco until the glass is full.