Which German sauce is a cold herb sauce traditionally associated with Frankfurt?

The cold herb sauce traditionally associated with Frankfurt is Frankfurter Grüne Soße.

Frankfurter Grüne Soße, or Frankfurt green sauce, is a chilled mixture based on several fresh herbs. Traditional Frankfurt descriptions identify seven herbs: borage, chervil, cress, parsley, sorrel, chives, and salad burnet. The herbs are combined with a creamy base that may include sour cream, yogurt, or similar dairy ingredients, depending on the recipe.

The sauce is commonly served with boiled potatoes and eggs, making it a recognizable spring and summer dish in Hesse. Frankfurt’s protected regional tradition emphasizes the specific herb blend, although household recipes can vary in proportions and preparation.

It should not be confused with pesto, chimichurri, or a warm parsley sauce. The Frankfurt version is usually served cold and has a fresh, tangy character. The herbs may be chopped finely or blended, but the identity of the sauce comes from its regional seven-herb tradition.