Soak bone marrow in cold water over night in the fridge

Blanch in boiling water for 30 seconds and cut into small cubes

Finely slice and dice shallot and garlic, finely chop parsley

Soften the sliced shallot and garlic in a pan with a splash of oil and a pinch of salt

Add herbs for reduction

Pour over the red wine reduce on a medium heat until one-third remains and strain

Sweat diced shallot and garlic with a splash of oil and a pinch of salt until translucent

Add the wine reduction

Add half of the reduced beef stock simmer for 10 mins 

Add remaining stock reduce to reach a spoon coating consistency

Turn off the heat and whisk in the bone marrow and butter a couple of cubes at a time until the sauce is velvety

Finish with white pepper, red wine vinegar and parsley