Season diced pork with salt. Heat the olive oil in a deep 12-inch sauté pan set over medium-high to high heat (use the most powerful burner on your stove). When the oil is hot, add the pork and sear on all sides until golden brown and almost fully cooked, lowering heat if needed to prevent burning. While the pork is browning you can use the time to dice the onions and peppers, mince the garlic and slice the chorizo. Set the pork aside and pour off about half the accumulated fat and reserve. Add the chorizo slices to the pan and brown on both sides; remove from pan and reserve.
Add the saffron threads to the white wine; set aside and let steep.
Make the sofrito: Add the onions and red peppers to the fat in the pan along with about 1 tsp. of Kosher salt. Cook about 5 minutes or so, until softened. Add the minced garlic and cook until fragrant. Add the tomatoes and cook over medium heat until the sofrito is reduced to a paste and is a deep burgundy-brown, stirring often to prevent sticking and burning. This process will take about an hour. The mixture will slowly evaporate, darken in color, and reduce by about three-quarters. If necessary, lower the heat and add some of the reserved fat to prevent sticking. The concentrated sofrito is what gives paella its depth of flavor and signature color so be patient with this process.
While the sofrito is cooking, prepare your chicken stock. Place the stock (or water) in a saucepot, add the bay leaf and the ancho chile, if using, and heat to infuse. When the liquid is hot, add about 2 ½ tsp. of Kosher salt, or to taste (if using clam juice, taste first as you may not need to add any salt). It should be seasoned enough as if you were making it to serve on its own. Cover and keep warm.
When the sofrito is close to being ready, remove the ancho and bay leaf from the chicken stock and heat the stock to a simmer. Raise the heat under the sofrito and add the smoked paprika and wine-saffron mix. Stir to scrape up the browned bits on the bottom of the pan and cook until the liquid is almost all gone. Add the reserved chorizo and the rice, stirring so that the rice is completely coated with the sofrito. Distribute the rice evenly in the pan and carefully pour the hot stock into the pan. Arrange the reserved pork over the rice and push the pieces in. Cook, uncovered and without stirring until the liquid has evaporated and the rice is al dente, about 20 minutes, lowering the heat as needed so that the liquid stays at a lively simmer. Move the pan over the burner occasionally so that the entire bottom is exposed evenly to the heat. Five minutes before the rice is done, arrange the julienned piquillo peppers and any optional garnishes over the rice. To develop the characteristic bottom layer of caramelized rice, raise the heat under the paella during these last few minutes of cooking and again move the pan over the burner to expose the entire bottom of the pan to the heat. Turn off heat, cover the paella with foil, and let settle for ten minutes before serving. Serve with lemon wedges.
If you do not have a large enough pan you can make this recipe in two 8 or 10-inch skillets, using half the amounts of ingredients for each pan.
Sofrito freezes very well. You can make large batches of sofrito ahead of time and hold it in the freezer and have it handy for making paella. Two cups of rice will take roughly the same quantity of prepared sofrito.
This recipe is ideal prepared in an 18-inch paella pan and done on an outdoor grill that has a surface area large enough for the pan, such as a round Weber grill.