Step 3:
Add wine, scraping any bits from bottom of pan. Add mussels and/or clams, if using. Cover and cook until clams and mussels open. Remove mussels and clams as they open and set aside. Discard any mussels or clams that do not open. Add tomato, oregano and chili flakes and bring to simmer. Season with salt and pepper. Cover and simmer over medium-low heat for 10 minutes. Add shrimp, squid and/or scallops and simmer until shrimp turn pink and opaque, about 2 to 3 minutes (if squid are cooked too long, they will become rubbery).