Wash, stem, and quarter strawberries. Spread out on a parchment-lined cookie sheet, and freeze for at least 1 hour (can be done the day ahead).
Run a wedge of lime around the rims of Champagne flutes, and dip each in a plate of sugar to coat rim.
Place 3 frozen strawberries in the bottom of each prepared flute. Open Champagne, and divide between all glasses (each should be approximately 2/3 of the way full). In a shaker filled with ice, combine tequila, limeade, and strawberry liqueur. Shake until chilled. Add a squeeze of fresh lime, if desired. Strain the cocktail into the Champagne-filled flutes until 3/4 of the way full.