In large saucepan, partially cook pasta in lightly salted boiling water for 6 minutes, or until still very firm—more firm than al dente. Reserve 1 1/2 cups pasta water and set aside. Drain remaining water from pasta and place pasta in large bowl.

Add oil to saucepan and heat just until shimmering. Add onion, garlic, and red pepper flakes. Sauté over medium heat until onion is soft but not browned, about 2 or 3 minutes. Add wine, tomatoes, and clams. Cover and cook, shaking pan a few times, until clams have opened, about 5 minutes. Lift lid and use slotted spoon to transfer clams that have opened to a separate dish.

When all clams are removed, add reserved pasta water and black beans to the saucepan and bring to a boil. Add partially cooked pasta and cook, tossing pasta with tongs several times, until pasta is al dente, about 2 more minutes.

Remove from heat and return clams and any accumulated juices to saucepan. Add parsley and toss to evenly mix. Divide among 6 serving bowls and drizzle with a little extra oil and a sprinkling of black pepper, if desired.