Step 1

Place mackerel, garlic, lemon zest, lemon juice, capers, 3 Tbsp. oil, and ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt in a large heatproof bowl. Season generously with pepper and toss to combine.

Step 2

Set bowl over a large pot of generously salted water (bottom of bowl should not be touching water) and bring water to a boil. Carefully remove bowl from pot and set aside. (Gently warming the ingredients here allows them to mingle nicely with the hot pasta later.)

Step 3

Cook pasta in same pot of boiling water, stirring occasionally, until al dente. Using tongs, transfer pasta, along with any water clinging to strands, to bowl with mackerel mixture. Add Parmesan, red pepper flakes, and ¼ cup pasta cooking liquid to bowl and toss pasta with tongs, adding more pasta cooking liquid by the tablespoonful if needed, until cheese is melted and pasta is coated evenly in sauce, about 1 minute.

Step 4

Divide pasta among bowls. Top with parsley, drizzle some oil over, and season with more pepper. Serve with lemon wedges for squeezing over if desired.