Heat the olive oil a heavy-based casserole or large saucepan set over a low heat. Add the onion and season generously with salt and freshly ground black pepper. Increase the heat to medium and add the bacon. Cook until the onions are soft and translucent (do not colour).
Add the breadcrumbs and a generous handful of herbs to the pan. Stir and then remove half of the mixture and set aside in a bowl to use in the sauce later. Transfer the remaining mixture to a blender.
Add the minced beef and pork to the mixture and pulse to form a paste. Stir in the egg yolk to combine. Use your hands to mould the mixture into small balls about the size of ping pong balls.
Put the meatballs in the casserole and fry until brown all over (this can take up to 10 minutes). Remove from the pan and set aside.
Add the reserved onion and bacon mixture to the pan. Deglaze by adding the red wine and scraping all the bits off the bottom of the pan. When the wine is boiling, add the chopped fresh tomatoes, keeping the heat high. Continue to cook, stirring all the time until they start to break down. Add the tinned tomatoes and a tin full of water. Bring back to the boil.
Taste to check the seasoning and cook for a further five minutes. Return the meatballs to the pan and bring to the boil, then lower the heat and simmer for 15 minutes.
Meanwhile, cook the pasta according to packet instructions.
To serve, mix the meatballs and pasta together with grated cheese, or keep separate if you prefer.