Preheat the oven to 200*C. Set a pan of water on the hob to boil. Get a skillet out to start browning your meat.
Throw the meat in the skillet to start browning and prepare the onion, carrot and celery. Throw this into the pan with the meat and crushed garlic. Cook gently for about 10 minutes until meat is completely brown. Throw in the tomatoes (break them up if using whole tomatoes), tomato paste, basil, vinegar, cayenne pepper and salt. Let this cook down for another 10 minutes or so until the carrot is soft. While this is cooking, prepare the leeks.
Slice the leek lengthways to almost the middle. It then unfolds into rather surprisingly large lasagna-shaped sheets. (Who knew!?) You want about 8 of these - depending on the size of your dish. I used one that was about 28cm by 20cm. Toss these into the boiling water and let them boil until soft - about 5-7 minutes. Rinse them in cold water when they are done. Chop up the middle part of the leeks that you aren't using as sheets and throw them in with the meat. Why not?
Let the leek sheets sit in cold water while you dish half the meat into your glass dish. Top with 4 leek sheets (this obviously depends on the dish size!).
Smear 100g of ricotta cheese onto the leek sheets. Top with the other half of the meat sauce. Add another layer of leek sheets. Top with the shredded swiss or cheddar cheese.
Bake in the oven for 20 minutes. Finish off under the grill if you fancy browning the cheese on top.
Let it sit for about 5 or 10 minutes. This not only makes it easier to slice, it also saves you from burning your tongue!