1½ cups short-grain rice (such as bomba or arborio)
¾ cup fresh or frozen peas
Place wood chips in a smoker box and place in the back corner of your gas grill. Preheat the grill to high heat, close the hood and let the chips preheat for 5-10 minutes. When you see smoke, reduce grill to medium heat.
Combine the chicken stock and saffron in a medium saucepan over medium-high heat and bring to a simmer. Add the clams, cover and cook until the clams open, 7-10 minutes. Transfer the clams to a bowl. Add the mussels to the broth, cover and cook until the mussels open, 7-10 minutes. Transfer to a bowl. Discard any shellfish that don’t open.
Brush the shrimp and scallops with olive oil, season with salt and pepper. Grill shrimp and scallops until slightly charred and just cooked through, about 1 minute per side. Transfer to a large plate.
Heat 4 tbsp butter oil in a 14-inch flameproof paella pan over direct medium heat on the grill. Add onion and cook until soft and translucent, 5- 7 minutes. Stir in garlic and cook until fragrant, about 30 seconds. Add rice, season with salt and black pepper, and stir to coat in butter. Stir in 4½ cups of the stock, cover the grill and cook until the liquid is absorbed and the rice is al dente, 20-25 minutes.
Fluff rice gently with a fork. Sprinkle peas over the surface, nestle cooked shrimp, scallops, clams, and mussels into the rice. Close the grill and cook another few minutes, to heat through seafood. Squeeze lemon juice over top and serve hot.