01 - Heat 2 tablespoons of olive oil in a large, heavy-bottomed pot over medium-high heat. Season the lamb cubes generously with salt and freshly ground black pepper. Brown the lamb in batches, ensuring not to overcrowd the pot, and transfer to a plate as each batch is done. Reduce the heat to medium. Add the finely chopped onion, diced carrots, and diced celery to the same pot. Sauté for 5-7 minutes, or until the vegetables have softened. Stir in the minced garlic and tomato paste, cooking for an additional minute until fragrant.
02 - Pour in the dry red wine, scraping the bottom of the pot to loosen any browned bits. Allow the wine to simmer and reduce for 2-3 minutes. Return the browned lamb to the pot. Add the crushed tomatoes, beef or chicken stock, fresh rosemary sprigs, fresh thyme sprigs, and the bay leaf. Bring the mixture to a simmer, then reduce the heat to low. Cover the pot and cook for 1.5 to 2 hours, stirring occasionally, until the lamb is exceptionally tender and the sauce has thickened.
03 - Remove and discard the bay leaf and herb stems from the ragu. Using two forks, shred the tender lamb directly in the pot, integrating it into the sauce. Taste and adjust seasoning with salt and freshly ground black pepper as needed.
04 - In a blender or food processor, combine the fresh mint leaves, extra virgin olive oil, and a pinch of salt. Blend until completely smooth. Strain the mixture through a fine-mesh sieve to obtain a vibrant green oil. Set aside.
05 - Cook the pappardelle pasta in a large pot of generously salted boiling water according to the package directions, until al dente. Reserve approximately 1/2 cup of the pasta cooking water before draining the pasta.
06 - Add the drained pappardelle to the pot with the lamb ragu. Toss gently to coat the pasta evenly. If the ragu seems too thick, add a little of the reserved pasta water to achieve the desired consistency. Plate the pasta immediately, spooning additional ragu over the top. Drizzle with the prepared mint oil in an artistic swirl. Garnish with freshly grated Parmesan cheese and extra mint leaves, if desired.