Whisk the grated 50 grams Pecorino Romano cheese, 5 grams pickled black peppercorns, and 1 teaspoon potato starch together until the cheese is evenly coated in the starch.
Bring the 4 cups water and 2 teaspoons salt to a boil over high heat and add the 250 grams pasta.
When the pasta is a little over a minute from being done, add a ladleful of the boiling liquid to the grated cheese mixture in a pan. Use a spatula to mix it together with the cheese to form a smooth sauce. Add more liquid if needed.
Then use a slotted spoon to transfer the pasta to the sauce. Turn on the heat and mix the pasta and sauce until it's thick enough to coat the pasta. If the pasta starts getting sticky, just add some more pasta liquid.