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Grilled Butterflied Leg of Lamb with Tomato-Fennel Vinaigrette

This grilled butterflied leg of lamb is a spectacular centrepiece for any outdoor gathering, offering a sophisticated twist on traditional barbecue fare. The lamb is marinated overnight in a pungent paste of rosemary, garlic, and anchovies, which ensures every slice is deeply savoury and incredibly tender. By butterflying the meat, you reduce the cooking time significantly while increasing the surface area for that delicious, charred crust that only a grill can provide.

As a diabetes-friendly main course, this dish focuses on high-quality protein and heart-healthy fats. The vibrant tomato and fennel vinaigrette provides a refreshing acidity that cuts through the richness of the meat without the need for sugary sauces. Serve this elegant roast with a crisp green salad or roasted Mediterranean vegetables for a balanced, low-carbohydrate meal that feels truly indulgent.

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Ingredients for Grilled Butterflied Leg of Lamb with Tomato-Fennel Vinaigrette

  • 9 garlic cloves, minced

  • 2 tablespoons chopped fresh rosemary

  • 2 anchovy fillets, minced

  • 2 teaspoons fennel seeds

  • 2 teaspoons coarse kosher salt

  • 1 1/2 teaspoons freshly cracked black pepper

  • 60ml extra-virgin olive oil

  • 1 (4- to 5-pound) butterflied leg of lamb, trimmed of excess fat and sinew (from one 13.8kg bone-in leg of lamb)

  • 1 1/2 teaspoons fennel seeds

  • 450g tomatoes, seeded, finely chopped (about 475ml )

  • 120ml Kalamata or Niçoise olives, pitted, finely chopped

  • 45ml red wine vinegar

  • 80ml extra-virgin olive oil

  • Coarse kosher salt

  • 1/4 cup thinly sliced fresh basil

How to make Grilled Butterflied Leg of Lamb with Tomato-Fennel Vinaigrette

Combine minced garlic, chopped rosemary, minced anchovies, fennel seeds, salt, and freshly cracked black pepper in small bowl or in mortar with pestle. Using sturdy wooden spoon or pestle, mash mixture into paste. Mix in extra-virgin olive oil. Rub paste thoroughly over both sides of lamb. Place lamb in 15x10x2-inch glass baking dish; cover with plastic wrap and refrigerate overnight. Let lamb stand at room temperature 1 hour before grilling.

Stir fennel seeds in small dry skillet over medium heat until fragrant and slightly darker in colour, about 2 minutes. Transfer to medium saucepan. Add tomatoes, olives, and vinegar. Stir in oil; season with salt and ground black pepper. Set aside.

Prepare barbecue (medium-high heat). Place lamb on grill rack. Cover barbecue and open vents; grill lamb until instant-read thermometer inserted into meat registers 54°C for medium-rare, turning occasionally, about 25 minutes. Transfer lamb to cutting board; let rest 10 minutes. Place saucepan with vinaigrette on slightly cooler part of barbecue and heat just until warm, about 5 minutes. Stir in thinly sliced basil leaves.

Cut lamb crosswise into 1/2-inch-thick slices. Transfer to platter. Spoon vinaigrette over and serve.

Disclaimer

While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.

Article history

The information on this page is peer reviewed by qualified clinicians.

  • 17 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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