Mix strawberries and sugar in a bowl and let stand for 5-10 minutes. Stir occasionally. Divide into two white wine glasses, add champagne and creme de cassis.
White Wine Glass
Rim a wine glass with strawberry liqueur and caster sugar. Blend all ingredients (except champagne) briefly with three-quarters of a glassful of crushed ice. Pour into the glass and add champagne. Garnish with a strawberry-half, and serve with short straws.
White Wine Glass
Blend all ingredients (except champagne) briefly with a glassful of crushed ice in a double-cocktail glass. Add champagne, garnish with a sugar-dipped strawberry, and serve.
Cocktail Glass