And we'll never, ever know.

Maybe this says more about my dad than the dish but come on, admit it, it says a lot about the dish.

Everyone cooks spaghetti bolognese - indeed it is now believed to be the most cooked dish in the world - and everyone secretly (or not so secretly, as the case may be) thinks theirs is the best.

But can there be such a thing as a ''secret ingredient'', something so strange it cannot be guessed? A bit of grated zucchini to get some greens into the kids? A bit of salami or a dash of tabasco to spice it up?

Absolutely not, says Giovanni Pilu, the owner of Pilu at Freshwater in Sydney and president of the Council of Italian Restaurants in Australia (CIRA), a body whose aim is to protect the integrity of traditional Italian cooking.

''It's nuts,'' Pilu says. ''Bolognese is like tiramisu or carbonara, it has been bastardised so many times in so many different ways over the years. You cannot substitute this for that, or add a bit of something and still call it ragu alla bolognese. Do not touch it!''

The first documented recipe for ragu alla bolognese, according to Wikipedia, was in an 1891 recipe book by the cook Pellegrino Artusi, who spent much time near Bologna in the north of Italy. It used lean veal fillet, pancetta, butter, onion and carrot, all finely minced and browned, then covered with broth, simmered slowly and finished with ''half a glass of cream''. There were no tomatoes and no spaghetti.

Certainly, no strictly traditional Italian chef today would serve ragu alla bolognese with spaghetti. The heavy sauce calls for the heavy lifting of fresh tagliatelle - the pasta being better at absorbing sauce and the wider shape keeping more sauce on the pasta, rather than leaving it in the bowl.

Carmelo Cipri, of Cipri Italian restaurant in Paddington, suggests ragu alla bolognese's link to spaghetti is most likely due to the postwar diaspora, when Italian immigrants - mostly from the south - brought their dishes to a new world: spaghetti was simply the best-known pasta served to a new audience. ''Spaghetti was just easier to sell, is how I see it,'' Cipri says, ''It was the first pasta everyone knew about outside Italy.''

An American authority on Bologna cuisine, Mary Beth Clark, says there are ''as many versions of ragu bolognese as there are versions of tomato sauce and pizza''.

Pilu says: ''Ragu alla bolognese has been changed and adapted through the ages and there is no right or wrong recipe.''

But there are versions, and there are versions. It seems widely acceptable, for example, to use garlic in the sofrito (the mix of vegetables) and to leave out the milk or cream, but not to deviate too far.

Antonio Di Santo, of artisan pasta company Laboratorio Di Santo, once heard of someone using barbecue sauce - a corruption that leaves everyone speechless. As do tabasco, zucchini and, ahem, Vegemite. So the key questions are these: which vegetables? Which meats? Which cooking liquids?

Both Di Santo and Antonietta Bevilacqua, of Stuzzichini Fine Foods in Gladesville, use garlic in their sofrito, alongside onion, carrot and celery. Cipri does not.

Di Santo uses pancetta, Bevilacqua does not. All use pork and veal - beef is acceptable, too.

Cipri adds pork ribs for extra flavour - ''the little bits of pork that come off the bone become a bit of a treat''. A tomato element - either canned, passata or concentrate - is included, as is red wine. Herbs and seasoning are a must.

Everyone agrees a long cooking time, between two and four hours, is crucial. ''I've heard some people put milk in to take the acid off the tomato,'' Bevilacqua says. ''That might be a bit more sophisticated but my cooking is like trattoria cooking. I am cooking like my mother and like her mother.''

Di Santo takes the seeds out of his fresh tomatoes to remove acidity and says it is important to use coarsely ground meat - too fine and the meat loses its flavour.

Pilu's restaurant recently featured menus from different Italian cities and when it came to Bologna, he took verifying the traditional nature of his bolognese sauce recipe seriously. First, he did his research online. Then he phoned Italian chef friends in Sydney and CIRA members, then he phoned friends and chefs in Italy. The recipe Pilu and his fellow CIRA members finally settled on as the most authentic was the one from the Accademia Italiana della Cucina - the Italian body established in 1982 to protect traditional cooking.

Classic bolognese ragu according to the Accademia Italiana della Cucina

150g pancetta, diced
50g carrot, diced
50g celery stalk, diced
50g onion, diced
300g beef cartella (thin skirt), ground
1/2 cup white or dry red wine
20g tomato paste
1 cup chicken stock
1 cup whole milk
Salt and pepper, to taste

Fry pancetta gently in saucepan. Add vegetables. Braise softly. Add beef and stir constantly until browned. Add wine, tomato paste and a little stock. Simmer for two hours. Over that time, gradually add milk, remaining stock, salt and pepper.

Serve with tagliatelle.

From: Good Living