First make your sauce. Place a large pan on the heat, add a good glug of olive oil, your onion and garlic, and fry slowly for 10 or so minutes, until soft. Add your oregano, the tomatoes, salt, and pepper and bring to a boil. Simmer for 15 minutes or so, then blend until smooth. Taste, it might need a tiny swig of red wine vinegar or some extra seasoning. 

While the tomatoes are simmering, chop the tuna up into 1-inch dice. Pour a good couple of tablespoons of olive oil into a large frying pan and place on the heat. Add the tuna to the pan with the pinenuts and cinnamon. Season lightly with salt and pepper and fry for a minute or so to cook the tuna on all sides and toast the pinenuts. Remove from the heat and put the mixture into a bowl. Allow to cool down for 5 minutes, then add the oregano, parsley, breadcrumbs, Parmesan, eggs, lemon zest, and juice to the bowl. Using your hands, really scrunch and mix the flavors into the tuna, then divide the mixture and squeeze it into meatballs slightly smaller than a golf ball. If you dip one of your hands in water while shaping, you’ll get a nice smooth surface on the meatball. If the mixture’s very sticky, add a few more breadcrumbs. Keep the meatballs around the same size and place them on an oiled tray, then put them in the fridge for an hour to let them rest.

Put the pan you fried the tuna in back on the heat with a little olive oil. Add your meatballs to the pan and jiggle them about until they’re golden brown all over. You might want to do them in batches- when they’re done, add them to the tomato sauce, divide between your plates, sprinkle with chopped parsley, and drizzle with good olive oil. Great served with spaghetti or linguine.