Heat stock in a separate stock pot. Crush saffron and add it to the stock or a little bit of white wine. Heat paella pan over medium heat, add olive oil and fry chicken until it begins to brown. Next add garlic and onions and saute until translucent. Add chorizo and cook until heated. Add the rice, stirring until well coated with oil. Add the paprika and grated tomato. Stir while cooking for a few minutes.
Add saffron flavored wine and hot stock. Bring to a boil while scraping the bottom of the pan. Now the rice should be level and you will not need to stir from this point on. Adjust heat to maintain a nice simmer. When the rice has absorbed a good amount of liquid but still has a soupy appearance add the mussels or clams. Once the rice is cooked add the shrimp or prawns tucking them down into the rice, then the piquillo peppers, artichoke hearts, green beans, beans and peas. During this time the rice should be carmelizing on the bottom of the pan or creating what is called the socarrat. It will make a faint crackling sound and smell toasty sweet but not burnt. Set aside to "rest" for 5-10 minutes. Sprinkle with chopped parsley, garnish with lemon wedges and serve.
OVEN: You can also use an oven if you find that your pan is too large to cook on the stove top, even with occasionally moving the pan around on the burner(s). Begin your recipe on the stove top but after adding the liquid carefully move your paella pan into the oven (350-400 degrees). Once rice is done return it to the stove top to create the caramelized layer of rice on the bottom of the pan.