Directions

1. To prepare the bone marrow, soak it in cold water in the fridge for at least 4 hours or overnight. Once soaked, bring a pot of seasoned water to a light simmer and add the bones for 45 seconds to 1 minute. Remove the bones and plunge them into an ice bath to cool completely.
2. Remove the marrow from the bones and dice into 1cm cubes. Leave in the fridge until ready to use.
3. In a large saucepan over medium-high heat, add the tallow (or oil). Once hot, add the beef trimmings with a pinch of salt and sauté until well browned.
4. Add the sliced shallots and carrots, and sauté for 4-5 minutes until they start to develop colour. Then add the rosemary, thyme, bay leaf, and celery. Deglaze the pan with the red wine.
5. Reduce the red wine by 4-5 times before adding the demi-glace. Bring it back to a simmer and reduce until the sauce reaches the desired consistency. It should have a pleasant mouthfeel, not too sticky or too thick.
6. Turn off the heat and add the parsley stalks. Let them steep in the hot liquid for 10-15 minutes, then strain the sauce through a fine sieve and cool.
7. When ready to serve, heat up only the amount of sauce you need. Once it reaches a gentle simmer, check the seasoning. Whisk in 1 cube of cold bone marrow per portion. Add the marrow to the hot sauce and whisk until fully emulsified.