Below, the recipe Donn's Delight calls for a teaspoon of grated onion and I would substitute onion juice. Mince the onion and using a wooden spoon, obtain the liquid. Discard the pulp.
A site about "competitive" foods; e.g., my chile is better than yours. Also covering food fermentations; sourdough bread, pickles, cured, and smoked meats, cheese, seafood, and food and foodways.