CILANTRO PESTO: Using a mortor and pestle or a spice grinder, crush or grind the peppercorns to a fine powder. Combine the pepper, cilantro roots and garlic; work the three inngredients innto a fairly smooth paste in the mortor or in a small blender or food processor. If you use a blender or food processor, you may need to add a little vegetable oil or water to ease the grinding. Make about quarter cup. For an industrial strength batch use 1 tb peppercorns, half cup cilantro roots and half cup garlic. To store the pesto for later use, put in a glass jar, pour a little oil onto the surface to cover it and seal tightly. It will keep nicely for about 1 week in the refrigerator. CLAY POT SHRIMP: Place the noodles in a large bowl and add warm water to cover. Soak the noodles until they become limp and white, about 15 minutes. Drain and set aside. You should have about 5 cups softened noodles. In a large clay pot or flameproof, heavy-bottomed casserole, heat the oil over medium heat until hot, about 1 minute. Add the pesto and stir-fry until fragrant, about 1 minute, adding a little more oil if it sticks or burns. Add the ginger and shrimp and stir-fry for 1 minute. Toss in the green onion, turning the mixture once more. Transfer the shrimp to a plate and set aside while you prepare the noodles and sauce. In a small bowl, combine the chicken stock, fish sauce (Nam Pla), oyster sauce, rice wine, soy sauce, sesame oil, sugar and salt; stir to mix well. Place the soaked noodles in the clay pot in which you cooked the shrimp mixture. Scrape the shrimp mixture over the noodles and pour in the chicken stock mixture. Toss the noodles and shrimp a little to combine them with the sauce, then cover the pot tightly. Place the clay pot over medium heat and cook until the noodles are soft and clear and the shrimp is done, about 10 minutes. Sprinkle with the cilantro leaves and serve at once.