Heat the olive oil in a wide paella pan or large shallow skillet over medium heat.
Add the shrimp and cook for about 1–2 minutes per side until lightly colored. Remove and set aside.
Add the squid and cook for 1–2 minutes, then remove and set aside with the shrimp.
Add the chopped onion and red bell pepper to the pan. Cook for 4–5 minutes until softened.
Add the minced garlic and cook for about 30 seconds.
Stir in the chopped tomatoes and cook for 3–4 minutes until they break down and become slightly thick.
Add the smoked paprika and saffron. Stir for about 30 seconds.
Add the rice and stir for 1–2 minutes so the grains are coated with the tomato mixture.
Pour in the seafood stock and white wine, if using. Add the bay leaf, salt, and black pepper.
Stir once to distribute the ingredients, then reduce the heat to a gentle simmer.
Cook uncovered for about 15 minutes without stirring, allowing the rice to absorb the liquid.
Add the mussels, fish, peas, and cooked squid. Arrange the shrimp over the top.
Continue cooking for another 5–8 minutes, until the rice is tender and the seafood is cooked through. Add a little more stock only if necessary.
Once the liquid is mostly absorbed, increase the heat slightly for 1–2 minutes to help form a light golden crust on the bottom of the pan.
Remove from the heat and cover loosely with foil. Let the paella rest for 5 minutes.
Remove the bay leaf, garnish with fresh parsley, and serve with lemon wedges.