Step 1. Prepare the Lamb Hearts

If not already cleaned, trim any fat or connective tissue from the lamb hearts. Rinse them under cold water and pat dry with paper towels. Season the hearts with salt and black pepper.

Step 2. Brown the Lamb Hearts

In a large heavy-bottomed pot or Dutch oven, heat the olive oil over medium-high heat. Add the lamb hearts and brown them on all sides, about 4-5 minutes. Remove the hearts from the pot and set aside.

Step 3. Sauté the Vegetables

In the same pot, add the chopped onion, carrots, celery, and garlic. Sauté over medium heat for 5-7 minutes, until the vegetables are softened and slightly caramelized.

Step 4. Deglaze with Wine

Pour in the red wine (or beef stock if preferred), scraping up any browned bits from the bottom of the pot. Let it simmer for 2-3 minutes to reduce slightly.

Step 5. Add Stock and Herbs

Return the browned lamb hearts to the pot. Add the beef or chicken stock, bay leaves, and thyme. Stir to combine and bring the mixture to a gentle simmer.

Step 6. Slow-Cook the Hearts

Cover the pot with a lid and reduce the heat to low. Let the hearts simmer gently for 1.5 to 2 hours, or until they are tender and infused with the flavors of the broth and vegetables.

Step 7. Season and Serve

Taste the sauce and adjust the seasoning with salt and pepper if needed. Garnish with freshly chopped parsley and serve the lamb hearts with crusty bread, mashed potatoes, or root vegetables.