Combine the sugar and 1-1/4 cup water in a small, heavy saucepan.
Place over medium heat and stir until the sugar is completely dissolved.
Boil the syrup for 5 minutes, then remove from the heat.
Add the coffee and liqueur.
Sprinkle gelatine over 1/4 cup water.
Allow to expand, dissolve over low heat, till transparent.
Add to coffee mixture.
Refrigerate until set but not frozen hard.
Beat to a mush, reset in freezer till softly frozen.
Scoop into deep bowls, serve right away.
Or put in tall glass, beat to a slush, serve with giant straws.
Serve immediately.
Making time: 20 minutes (excluding setting time)
Makes: > 5 servings
Shelflife: 2-3 days