Place sugar in a large wide mouthed jar. (If you don’t have a
wide-mouth jar around the house, a well-washed plastic gallon milk jug and
a funnel work very well.) Warm vodka, pour over sugar and stir or shake
until almost all is dissolved. Place frozen raspberries into jar/jug.
Cover loosely and allow to stand for about 3 weeks, stirring or shaking gently
daily. Strain cordial and funnel into gift bottles. Serve alone
or mixed with lemon-lime soda or seltzer.