I found the recipe you are talking about. While I have never eaten at the Sci-fi to know if this is exactly like their recipe, I make one that I think is close.
http://www.hillbillyhousewife.com/cucumber-and-onions-in-vinegar.htm
Cucumber And Onions In Vinegar
This is such a simple dish, but these
cucumber and onions in vinegar are so delicious during the hottest weeks of the summer.
- 4 medium size cucumbers
- 2 small vidalia onions
- 1/3 cup white vinegar
- 1/3 cup sugar
- 1/2 tsp salt
Slice cucumbers and onions thinly. Combine vinegar,sugar and salt in a small bowl and pour over cucumbers and onions. Chill in the fridge and drain the juice before you eat them.