There are always variations with classic recipes and, sure, you can be lazy and slap a jar of Dolmio into some mince but if you want to make an authentic Bolognese sauce help is at hand.
In 1982 the Italian Academy of Cuisine (Accademia Italiana della Cucina), an organization dedicated to the culinary heritage of Italy, registered a recipe for Bolognese sauce (Ragł classico Bolognese) with the Bologna Chamber of Commerce. This confines the ingredients to beef, fresh bacon (pancetta), onions, carrot, celery, tomato sauce or tomato paste, meat broth, dry wine (red or white), milk, salt and pepper.
This is my understanding of a Bolognese sauce, which strays a little from the approved recipe but even the Accademia acknowledge there are different traditions. Garlic and herbs aren't on the approved list, nor sugar (but I think it makes tomatoes less tart). Slimmers can use lean steak mince but it's the fat in the beef that assists the cooking process and creates a richer sauce.
1 clove garlic, crushed 50g pancetta, finely chopped (I use ready chopped tubs of 'cubetti') 500g minced beef
200ml white wine
1 tin chopped tomatoes (400g)
1 tsp brown sugar (or to taste)
1 bay leaf
½ tsp dried thyme
In a medium sized pan fry the onions in olive oil over a medium heat for a few minutes to soften. Add the carrot and celery and fry for several minutes more. Add the pancetta and, when sealed, begin adding the mince gradually, breaking it into the pan with a fork (if you add it all at once the liquid may overwhelm the pan). Fry until browned adding the garlic towards the end so as not to burn it. Season.
Raise the heat to the highest setting and add the wine, reducing the liquid for about 5 minutes. Then add the milk, again reduce for 5 minutes. There may some liquid in the pan, don't worry about boiling it all off. Add the tomatoes, the bay leaf, thyme, sugar and seasoning. Lower the heat so the mixture is barely simmering and cook for 1½ hours or until almost all the liquid has evaporated. Stir regularly, especially towards the end when the sauce thickens.
Many serve Bolognese with spaghetti (myself included) however, if you want to be strict, tradition apparently dictates the pasta should be tagliatelle. Top with a grating of parmesan and a grind of pepper.