Slice your pancetta thinly across the grain, or if you're like me you can just cube it.
Add the olive oil to a large pan, turn on moderately low heat, cook for about 5 or so minutes.
Add the onion to the pan and continue to cool to soften the onion. Depending on heat this will take 10 to 15 minutes. Stir it occasionally to keep it cooking evenly.
Add the red pepper flakes and parsley to the pan. Cook for about 3 to 5 minutes.
Add the red wine vinegar and allow that to simmer until it evaporates. Depending on heat this will take 3 to 5 minutes.
Add the San Marzano tomatoes and minced garlic, bring this to a boil stirring as it cooks. Try to break the tomatoes up as much as possible by sort of squashing them with the back of a wooden spoon. Once it boils you can then reduce it to a simmer. I left mine uncovered and cooked it for about an hour, stirring occasionally.
At this time you want to bring a large pot of water to a boil for the noodles.
Bring the pan back to a boil and add the tomato paste, reduce to simmer and allow it to cook for about 20 to 30 minutes longer. This will thicken the sauce and give it a beautiful colour and texture.
If desired you can hit it with some salt but with the pancetta you likely don't need to, personal choice.
Salt your boiling water, then add your pasta. Cook for 1 minute less than the package tells you to. I cooked mine for 6 minutes.
If you're using a huge saute pan you can continue using that. If not I would recommend transferring the sauce to a dutch oven so you have enough room to mix the pasta properly.
Bring your sauce to a medium heat, add ¼ to ½ cup of the pasta water to it. I recommend starting with ¼ cup, then taste the pasta after adding the cooked pasta.
Drain your cooked pasta and pop that into your sauce. Stir until it all comes together. Add more pasta water if needed. Continue to stir until it is well combined.
Remove from heat and transfer it to a large serving bowl.
Top with cheese.
Serve with a big old pasta loving smile!