Sous Vide Lamb Rump Cap

August 31, 2023

Sous Vide Lamb Rump Cap

Lamb rump cap is the lamb’s rump - a tender, relatively lean cut under a thick layer of fat, with a strong and distinct lamb flavor. Because the meat is already tender, it doesn’t need the long, slow cooking of a tough roast. The sous vide method takes advantage of exactly that: the meat is cooked at a low, precise temperature in a water bath so it turns evenly pink from edge to edge, and is then browned hard in a pan or on the grill for color, crispness and flavor.

The recipe uses two rump caps of about 400 g (14 oz) each, seasoned with salt, pepper, garlic and rosemary, and cooked in a water bath at 133°F (56°C) for 3.5-4 hours. The fat side is lightly scored before the meat is vacuum-sealed - this gives the seasoning better grip and more even browning afterward, not to tenderize the meat. When the bag comes out of the water, the meat is patted completely dry and browned quickly over high heat with a basting of melted butter, garlic and rosemary, so it gets a crisp, golden surface without the already tender meat overcooking.

Lamb rump cap is often associated with Easter dinner and other occasions where something a little finer is served. Serve it sliced thinly with crushed or small potatoes, a fresh mint or tzatziki sauce, ratatouille or a mixed green salad.

Ingredients

Serves 4

2 lamb rump caps, about 400 g each (about 800 g total), trimmed of sinew
4 g salt per cap (about 0.5% of the meat’s weight)
freshly ground black pepper, to taste
1-2 cloves garlic, coarsely chopped
2-3 sprigs fresh rosemary (or 1½ tsp dried rosemary)
50 g butter, for browning (clarified or regular)

Directions

Pat the lamb rump caps completely dry, and carefully score the fat side in a crosshatch pattern without cutting into the meat itself. Season the meat evenly with salt and pepper, and add the dried rosemary directly onto the surface if using. Place the rump caps in a vacuum bag and vacuum-seal at maximum vacuum.

Preheat the sous vide water bath to 133°F (56°C), and only put the bag in the water once the temperature is reached. Cook the lamb rump caps in the water bath for 3.5-4 hours.

Take the bag out of the water, open it, and pat the meat completely dry with paper towels - it’s crucial for a good crust that the meat isn’t damp when it hits the hot pan. Heat a pan or a grill to high heat, and brown the rump caps hard, fat side first, about 30-40 seconds per side (2-3 minutes on the fat side if grilling). Add the butter, the chopped garlic and the rosemary sprigs to the pan toward the end of the browning, and baste the meat continuously with the melted butter for about a minute, so it takes on extra flavor and a glossy, golden surface.

Let the meat rest uncovered for 5-10 minutes, so the juices settle. Then slice the rump caps thinly across the muscle fibers, and arrange at once on preheated plates.

Notes

The lamb rump cap can easily be prepared well in advance. After the sous vide cooking, the sealed bag is cooled quickly and can be kept in the fridge for up to a week. Reheat the bag in warm tap water for about an hour before browning the meat as described.

If you prefer a result with a touch more pink, the water bath can be lowered to 131°F (55°C) - still for 3.5-4 hours. Avoid going beyond 4 hours in the water bath: lamb rump cap is already a tender cut, and too long (6-8 hours) gives a liver-like, unpleasant texture.