1 1⁄2 pounds littleneck clams
1 pound mussels
1 pound head-on jumbo shrimp
8 oz calamari rings
1⁄2 cup olive oil, plus more for drizzling
3 teaspoons kosher salt, divided
2 teaspoons smoked paprika, divided
6 cups chicken stock, plus extra as needed
Large pinch saffron threads (about 1⁄2 teaspoon)
10 ounces dried Spanish chorizo, chopped
2 leeks, white and light green parts only, halved lengthwise and thinly sliced
1 onion, finely chopped
4 cloves garlic, chopped
1 Fresno chile, seeded and minced
1⁄2 red bell pepper, finely chopped
1 bag frozen peas
2 medium summer squash, quartered and cut into 1⁄4-inch strips
2 sprigs fresh thyme
3⁄4 cup dry white wine
4 plum tomatoes, grated on a box grater, skin discarded
1 tablespoon tomato paste
3 cups short-grain Spanish rice, such as Bomba or Arborio
2 lemons, 1 halved and 1 cut into wedges
Small handful fresh parsley, finely chopped, for serving
Scrub the clams under cold water. Transfer them to a large bowl and cover with cold, very heavily salted water and soak for 2 to 4 hours in the refrigerator to express any sand.
Scrub and debeard the mussels. Transfer them to a bowl and cover loosely with a damp paper towel; place in the refrigerator. Place the shrimp in a bowl and drizzle with the olive oil. Toss with 1 teaspoon of the salt and 1 teaspoon of the paprika. Place in the refrigerator.
Pour the stock into a medium saucepan and sprinkle it with the saffron, crumbling it between your fingers. Heat over medium heat until warm and steaming.
Preheat the grill over medium-high heat to 400F. Heat the olive oil in a 16-inch paella pan. Add the chorizo and cook, stirring occasionally, until most of the fat has rendered, about 5 minutes.
Add the leeks and onion to the pan and sauté, stirring occasionally, until soft and translucent, about 3 minutes. Add the garlic and chile and sauté for 1 minute. Add the bell pepper, squash, thyme, the remaining 2 teaspoons salt, and the remaining 1 teaspoon paprika. Cook, stirring occasionally, until the vegetables have softened, about 4 minutes. Pour in the wine and scrape up any browned bits that may have stuck to the bottom of the pan. Cook until most of the wine has evaporated, about 1 minute. Stir in the tomatoes and tomato paste and cook, stirring occasionally, for 5 minutes.
Add the rice to the pan and toast, stirring occasionally, 2 to 3 minutes. Pour in the warm stock and stir to combine. Do not stir the paella from this point on. Close the grill and cook for 15 minutes.
Bury the clams, calamari, and mussels in the rice and press the shrimp on top at this point we decided to add a bag of frozen peas over top. If the rice seems dry, add another 1⁄2 cup of chicken stock. Loosely tent the pan with foil. Close the grill lid and cook until all of the clams and mussels have opened and the shrimp is opaque, 12 to 15 minutes. (Discard any clams or mussels that haven’t opened.) Remove the paella from the heat and cover tightly with foil. Let it sit for 10 minutes.
Just before serving, squeeze the lemon halves over the paella and sprinkle with parsley. Serve with lemon wedges on the side.