Authentic Spanish paella recipes are available at La Tienda, the Spanish Cuisine and Spain Recipes. These recipes make a mixed paella with chicken and seafood, but Spain Recipes links to additional versions of the dish, including a vegetarian version. The flexibility of paella leaves cooks room to experiment with different ingredients.
The paella recipe at La Tienda calls for smoked Spanish paprika, saffron, jamon serrano ham and chorizo for an authentic Spanish flavor. The Spanish Cuisine's recipe lists fish broth instead of chicken, medium-grain rice instead of short-grain, and tomatoes instead of peas. The versions of paella at Spain Recipes include mushroom, chicken-only, chicken and shrimp, Catalan-style monkfish, and chile and scallop. Spanish chefs traditionally make paella in a paellera, or paella pan, and villages sometimes have giant versions of them at festivals. Cooks who lack a paella pan may use any wide, two handled pan, and one recipe uses a pressure cooker.
Paella originally comes from Valencia in eastern Spain, though the cooks there don't typically mix seafood and chicken. Spanish restaurants usually serve mixed paella, which is what most people recognize as the famous dish. Other rice dishes that resemble paella are black rice, popular along the Mediterranean coast of Spain, and arroz con costra, a crusty rice with spare ribs and chicken that comes from Murcia.