Passum is a sweet wine made from dried grapes, similar to a thick raisin paste or syrup. It can be substituted with high-quality grape must or a mixture of raisins and wine reduced down.
Liquamen was a Roman fish sauce. Modern substitutes include fish sauce (like Nam Pla or Nuoc Mam) or soy sauce for a vegetarian alternative.
This dish can be served as a starter or a light main course. It pairs well with crusty bread or as a topping for polenta.