Quick tip: If you like to add a splash or two of vinegar to your potato salad, add it while the potatoes are still hot. The warm potatoes will absorb the vinegar. Vinegar added to cooled potatoes will not flavor them nearly as much, but rather just blend into the mayonnaise (or sour cream and yogurt, as the case may be).
The same principle holds true for other starch and grain salads. If you’re adding some fruit juice to a wild rice salad, for instance, toss it with hot rice to fully flavor the grains.
Here’s a potato salad recipe that puts this technique to use. Cool the potatoes just enough so they don’t burn you as you handle them, then toss them with vinegar while still very warm.