If you ever go to a restaurant and you can’t figure out what made something taste amazing it’s usually: loads more butter, loads more cream, loads more garlic, celery salt, lemon salt, mustard powder, monosodium glutamate, vinegar, or some combination of the above, so add those things one at a time until you figure it out.
Want to know why that potato salad was amazing? They added a teaspoon of mustard powder and half a teaspoon of white wine vinegar to it most likely.