In a large pot or Dutch oven, heat some olive oil over medium-high heat. Add the onion, bell peppers, and garlic, and cook until the vegetables are soft and fragrant, about 5 minutes.
Add the mixed seafood to the pot and cook for another 2-3 minutes, or until the seafood is lightly browned and just cooked through. Remove the seafood from the pot and set aside.
Add the short-grain rice to the pot and stir well to coat the rice with the remaining oil and juices. Cook for 2-3 minutes, or until the rice is lightly toasted and fragrant.
Pour in the fish or vegetable broth, white wine, smoked paprika, bay leaf, and salt and pepper to taste. Stir well and bring to a boil.
Reduce the heat to low, cover the pot, and simmer for 20-25 minutes, or until the rice is tender and has absorbed most of the liquid. Stir occasionally to prevent the rice from sticking to the bottom of the pot.
Once the rice is cooked, return the cooked seafood to the pot and stir well to combine. Simmer for another 2-3 minutes, or until the seafood is heated through.
Serve the arroz caldoso hot in individual bowls, garnished with lemon wedges. Enjoy your warm and delicious Spanish soupy rice!