Combine the fish broth, pimenton and salt to taste in a soup pot and keep warm over a low flame. Meanwhile, heat the olive oil until nearly smoking in a 16-inch paella pan set on a barbeque or paella burner or stradling 2 burners. Add the prawns and cook, flipping occasionally, for 6-7 minutes or until a bit browned. Remove to a plate and then add the lobsters to the pan, shell side down and cook 4-1/2 minutes, flip, and then cook for another 4-1/2 minutes. Put the lobsters on the plate with the prawns. If the pan is a bit dry, add a few more Tablespoons of oil. TTurn the heat down to medium, add the onions, pepper and garlic, and cook, stirring, for about 10 minutes, or until just softened. Pour the rice into the pan, in an even cross) (this is the way I was taught and I don's mess with tradition) and then stir to combine with the vegetables. Add the broth, bring to a boil, and then lower the heat to simmer and cook for 10 minutes. Arrange the prawns, lobster, clams and fish on top of the rice, cover with 1-2 large piece of tinfoil, add cook for 10 minutes. Remove the tinfoil and cook 5 more minutes. The clams should be open and the rice cooked through. You might start to hear a crackling sound -- this is a good thing, it means your'e forming a crust at the bottom of the pan (the "soccarat"), which distinguishes all great paellas. Remove the pan from the heat sourse, cover with you piece of large tinfoil, and let it sit undisturbed for 15 minutes before serving, sprinkled with parsley.
Bring the pan to the table, scoop plenty of everything onto everyone's plates, and encourage your guests to squeeze lots of lemon on their dinner.