Peel and chop the onions and garlic finely.
Put the oil in a heavy-based casserole over a low heat and warm through. Add the onions and cook till soft and translucent.
Meanwhile, peel and chop the vegetables. Chop the celery and half the carrots into a fine dice. Chop the remaining vegetables into chunks - around 2cm square for the carrots and largish slices for the fennel.
Add the garlic, celery and finely diced carrots into the onions and continue to cook.
Put the oven on to pre-heat at 170C.
Chop the sausages into chunks and dice the bacon if using that rather than cubed pancetta.
Put the pancetta or bacon into a frying pan and sear over a moderate heat so that the fat runs and the meat starts to turn a golden brown.
Remove the pancetta from the pan and add the sausage chunks. Brown on all sides.
Put the cooked pancetta and sausage into the casserole along with the remaining vegetables, the chopped tomatoes, the herbs and red wine or stock.
Season well with salt and pepper and bring to a gentle simmer on the hob, before covering and transferring to the oven for 30 minutes. Remove the lid for the last 10 minutes of cooking to help reduce down the sauce.
Serve with a garnish of fresh parsley.
