Directions

1. Heat a large saucepan over medium-high heat and add a couple of tablespoons of oil.
2. Once the oil is hot, add the lamb trimmings with a pinch of salt and sauté until they are well browned.
3. Add the butter, along with the carrot and three roughly sliced shallots, and cook until golden brown.
4. Stir in the celery, garlic, and tomato purée.
5. Add the rosemary, thyme, and half the sherry vinegar, scraping the pan to deglaze it.
6. Pour in the stock, bring to a gentle simmer, and reduce by about one-fifth.
7. While the stock is reducing, finely dice the remaining two shallots and set them aside.
8. In a small pan, sauté the diced shallots in a little butter with a pinch of salt, then set aside.
9. Once the stock has reduced, strain it through a fine sieve into a clean pan, discarding any solids.
10. Bring the strained stock to a light simmer and adjust the seasoning with salt and more sherry vinegar, to taste.
11. Stir the sautéed shallots into the sauce.
12. Dissolve 2 tablespoons of cornflour in an equal amount of water to form a smooth slurry.
13. Gradually stir the cornflour mixture into the simmering stock, stirring continuously until the sauce thickens slightly.
14. Cook for 3–4 minutes, checking the thickness. If the sauce is too thin, repeat the process with more cornflour slurry until you achieve the desired consistency.
15. Remove from the heat, check the seasoning, and transfer the sauce to a container to cool to room temperature.
16. Once cooled, store the sauce in the fridge for up to 2–3 days.
17. To serve, reheat the sauce in a pot over a gentle heat, bringing it to a light simmer for 3–4 minutes.
18. Taste and adjust the seasoning one final time before serving.