Combine the following in a saucepan:
 

• 1 cup distilled white vinegar
• 1 cup white sugar
• 1 teaspoon salt

Bring to a boil, stirring until dissolved, boil gently for 1 minute, and remove from heat.  Let solution cool to room temperature.

Slice one large peeled cucumber and an onion in thin slices.  Pour the cooled vinegar "dressing" over the veggies and serve.