Cut the onion into small cubes. Trim the thick skin from the bottom of the guanciale and the top seasoning layer. Slice the guanciale into long strings.
Add the onion, the guanciale, and the olive oil to a medium frying pan. Let saute' for 18 minutes at medium heat. Once the guanciale is crispy and golden, pour the wine. Let the alcohol evaporate for a few minutes.
Pour the cherry tomatoes into the frying pan and let them cook for 10 minutes. Stir occasionally and then add the salt.
In the meantime bring the water to boil into a tall stockpot. Once the water is boiling add the pasta. I don't recommend adding salt into the water, as the sauce is already quite salty.
Cook the pasta until al dente. To achieve pasta al dente follow the recommendation on the packet. Usually, there are two different cooking times, choose the lower number. If there is just one cooking time, cook the pasta for two minutes less than the advised time.
Now, add the passata into the frying pan and cook it for 10 minutes until reduced slightly.
Just before draining the pasta, set aside two soup ladle spoons of water from the cooked pasta into a cup to use later. Drain the pasta and add it into the sauce with a handful of grated pecorino Romano. Mix together with the water from the cooked pasta for a few minutes on medium heat until combined.Don't overcook it otherwise the sauce will dry up. We want the sauce to be slightly watery. Serve the pasta immediately with a generous handful of grated Pecorino Romano. Buon appetito!