Ius in Murena Elixa (Sauce for Poached Moray Eel) is a traditional Ancient Roman recipe for a classic sauce of pepper, lovage, caraway seeds, cumin, nuts, dates and mustard in a honey, vinegar, stock, oil and defrutum base that's intended to be served with poached moray eel. The full recipe is presented here and I hope you enjoy this classic Ancient Roman version of: Sauce for Poached Moray Eel (Ius in Murena Elixa).
Combine the black pepper, lovage (or celery) seeds, caraway seeds, cumin seeds, and mustard powder in a mortar. Pound to grind then add the almonds and dates and pound again. Mix in the honey, white wine vinegar, defrutum, liquamen, fish stock and olive oil then turn into a saucepan. Bring to a boil, reduce to a simmer and cook gently for 20 minutes, or until thickened.