Debone the lamb leg, roughly chop half of it with a knife and set aside the rest for another dish.
Crush the bones and toast them in the oven, then put them in a saucepan covered with water and boil for about half an hour uncovered. The liquid should reduce to about a third of the initial volume and be collected, straining the bones well through a sieve or a colander: this will produce a brown lamb stock to flavor the sauce.
Chop the onion, one garlic clove and sauté very gently in a large pan with a drizzle of oil; add the chopped lamb meat and brown over high heat.
Deglaze with half a glass of wine, add salt, pepper, a sprig of thyme and four juniper berries.
After about 5 minutes, cook the pasta.
After another roughly 5 minutes, add the brown stock, another sprig of thyme, and chopped dried prunes to the lamb sauce.
Drain the pasta, removing it a couple of minutes before the time on the package, then toss in the pan to coat with the sauce over high heat. Serve hot.