Cornish 21-Day Dry-Aged Grass-Fed Fillet of Beef

Chef’s Tip: Cooking a Whole Grass-Fed Beef Fillet

Grass-fed beef fillet is the crown jewel of roasts—exceptionally tender with a clean, deep, natural flavour. However, because grass-fed beef is leaner than grain-fed beef, it cooks roughly 30% faster and can dry out quickly if overdone. Target a strict medium-rare ($52^{\circ}\text{C}$ to $54^{\circ}\text{C}$) to keep it succulent.

1. Tying & Prepping: Trim any silver skin with a sharp knife. Because a whole fillet tapers at the tail, fold the thin end underneath itself and tie the whole roast tightly with butcher's twine at 2-inch intervals. This creates a uniform cylinder so every slice cooks evenly.

2. Salt Early, Temper Long: Remove the meat from the fridge 1 hour before cooking. Season generously with flaky sea salt and cracked black pepper. Letting it come to room temperature is critical for even heat distribution.

3. The Sear-First Approach: Preheat your oven to 200 celsius or 180 celsius for fan ovens. Heat a roasting tin or large pan over high heat with a splash of oil. Sear the fillet for 4–5 minutes, turning until a deep golden crust forms on all sides.

4. Baste & Roast: Toss 50g of unsalted butter, a few smashed garlic cloves, and sprigs of fresh thyme into the tin. Transfer straight to the oven and roast for 18–22 minutes for medium-rare (use a meat thermometer in the thickest part—pull it out at $50^{\circ}\text{C}$ as carryover cooking will raise the temperature by $3–4^{\circ}\text{C}$).

5. The Non-Negotiable Rest: Transfer the fillet to a warm board, spoon the pan juices over top, cover loosely with foil, and let it rest for 15–20 minutes before carving. This allows the muscular fibers to relax and redistribute the juices throughout the meat.