Place the 2 large cucumbers, sliced and 1 medium red onion, in a medium sized mixing bowl.
Combine the 1/2 cup white vinegar, 1/2 cup water and 1/4 cup granulated sugar in a small saucepan over medium-high heat. Heat until it boils and the sugar has dissolved completely.
Remove mixture from heat; immediately pour over cucumbers and onions. Cover and refrigerate for at least 4 hours, up to 72 hours.
Notes
Can substitute white onion for the red onion
Can substitute apple cider vinegar for the white vinegar (apple cider vinegar is slightly sweeter)
This recipe can easily be doubled or tripled
Cucumbers will continue to release liquid as they are allowed to sit in the refrigerator