www.allrecipes.com/recipe/228394/sweet-and-tangy-thai-cucumber-salad

1/4 C sugar
1/2 C hot water
1/3 C vinegar
1 t salt
1 large cucumber, sliced thin
1 red onion, sliced thin

Mix sugar, water, salt, and vinegar in a small bowl until dissolved. Add
in the cucumbers and onion and refrigerate at least 1 hour.