I’m infamous at the farmers market for my cranky diatribes about the overuse of the word raab, but this one is legit. (Without going into the curmudgeonly details, just know that the German raab derives from the Latin rape - pronounce it the Italian way: rah-pay - which means turnip.)
As with most bitter greens, a quick bath in well-salted, boiling water mellows the tang. This parboiling also helps render the rapini tender and luscious. Get a few quarts water bubbling away, add a handful of sea salt, and gently lower the entire bunch of rapini into the pot, stem end first.
After about 2 minutes (that’s 2 minutes total in the water, not after it returns to a boil) set tongs to lift the greens from the pot. You can save the water to cook pasta or vegetables if you want. Let the rapini cool a bit, then cut it into roughly 2-inch pieces.
Soak a couple of tablespoons (or more if you want extras) of Pantellerian salt-packed capers in water for about 15 minutes. Drain and pat dry with a towel. Cover the bottom of a skillet with extra virgin olive oil, heat it until it shimmers, and fry the capers over medium-low until they’re crispy about 10 minutes.
Use a slotted spoon to remove the capers from the skillet and set them aside. Add the rapini (it’s okay if it still got some cooking water clinging to it) and a few cloves of chopped garlic. Cook gently for about 10 minutes, then add the capers and a tablespoon of Son fish sauce. Taste and add salt if needed.