Directions

1. Bring a large pot of salted water to a boil. Add pasta, and cook according to package directions for al dente, about 13 minutes. Reserve 1 cup pasta cooking liquid. Drain pasta; set aside.
2. Heat oil in a large Dutch oven over medium-high. Add onion, garlic, and crushed red pepper; cook until fragrant and onion is softened, about 2 minutes, stirring occasionally. Add tomato paste, and stir for 1 minute. Add wine; whisk to incorporate. Bring mixture to a boil. Add clams; cook, covered, 2 minutes. Add mussels, and cook, covered, until shells open, 4 to 5 minutes. Transfer shellfish to a medium bowl, discarding any that did not open.
3. In a medium bowl, crush canned tomatoes by hand; add to Dutch oven along with tomato juice from the can. Add oregano and salt, and bring to a simmer over medium-high. Cook, stirring occasionally, until sauce is slightly thickened and flavors meld, about 10 minutes.
4. Stir in shrimp. Cook, stirring often, until shrimp are just cooked through, about 3 minutes. Stir in cooked pasta and shellfish. Add 1/4 cup reserved cooking liquid, stirring to coat and evenly heat through, about 2 minutes. (Add additional cooking liquid as needed.) Remove from heat, and add crushed red pepper and salt to taste. Garnish with oregano, and drizzle each serving with olive oil, as desired.