Sprinkle the ground meat generously with salt and pepper. Set aside.
Slice the onions and garlic coarsely. Slice the carrot into thin rounds as well.
Place the French oven or heavy stockpot over medium-high heat. Add olive oil to cover the entire bottom of the container.
Once the oil is hot, add the lamb and cook until they turn deep brown in colour. Do this in batches as much as possible.
After the lamb has been browned thoroughly, add the onions, turn the heat into the medium setting, then cook for around 10 minutes or until the onions become golden in colour.
After 10 minutes, add the sage, rosemary, carrots and garlic. Reduce the heat to a low, then sauté the vegetables lightly for about 5 minutes or until they become soft.
Pour the wine into the mixture and bring to a boil for about 10 minutes.
Using the back of a spoon or fork, crush the canned plum tomatoes. Add the tomatoes along with their juices into the pot.
Simmer, cover, and place the mixture into the 275-degree Celsius oven. Bake for 3 to 4 hours. If using a slow cooker, cook the ingredients on a high setting for 4 hours or on a low setting for at least 8 hours. The longer you cook the dish, the more tender the meat will become.
Pour the ragu over pasta and serve with freshly grated Parmesan cheese on top.