Ingredients

• 3 medium lemons, divided

• ⅔ cup extra-virgin olive oil

• ½ cup chopped fresh flat-leaf parsley

• 2 teaspoons chopped fresh oregano

• 2 cloves garlic, grated

• ½ teaspoon salt

• ½ teaspoon crushed red pepper

• 2 tablespoons white vinegar plus 1/2 cup, divided

• 1 medium fennel bulb, cored and very thinly sliced

• 1 cup thinly sliced red onion

• 16 cups water

• 1 pound peeled and deveined medium shrimp

• 1 pound large scallops

• ½ pound squid (tubes), cleaned and sliced into 1/4-inch rings

• 1 (4.2-ounce) can smoked mussels in olive oil, drained