Chop and clean Rapini. Remove each leaf. Stems, if you are keeping them as Nonna does, need to be individually-peeled so that the outer husk is removed. You'll place the separated greens in water and wash and rinse them 3-4 times. Chop/slice the tomatoes and onions so that they are ready to go.
In the pot, add extra virgin olive oil, tomatoes, onions, salt and pepper.
Place all of the prepared/cleaned greens into the pot.
Add two cups of filtered water.
Place the pot on the stove at medium-high heat, and stir the ingredients together.
Cover the pot. It will take 2-3 minutes to get to a boil.
Once it comes to a boil, uncover and stir. Lower the heat to medium-low.
Cover, and cook for 15 minutes.
Stir again, and cook with the lid on, for a final 5-10 minutes, depending on the tenderness you are going for.
Add salt, only if you think it is necessary, to-taste, after the greens are completely cooked. Red pepper flakes on the side can be added when serving. To store left overs, allow to completely cool, cover in a container and store in the refrigerator for no more than four days.