Make shrimp stock by adding one quart of water to a pot. Add shrimp shells and heads, roughly chopped onion and garlic. Boil for 30 minutes. Using a hand-held blender, blend all the contents until all roughly pulverized. Boil for another 10 minutes. Turn off heat and strain through a fine sieve and set aside. You should have about 2 cups.
In a large sauce pan, heat the oil over medium-high heat. Fry garlic, stirring constantly, until golden brown. Remove and set aside. Fry pork in remaining oil until brown and crisp. Add the tofu and shrimps and sauté. Add ½ cup of the shrimp broth, cover and boil. Add the celery and garlic and season with salt and pepper. Remove to plate and set aside.
Soak the achuete (annatto seeds) in hot water. Add this coloring to the remaining shrimp broth and put the mixture into sauce pan. Bring to a boil and add the flour/water mixture. Stir constantly until thickened. This is the red sauce for the pancit called “palabok”.
Meanwhile, boil about 2 quarts of water. Lay out the lug-lug noodles in a large roasting pan or large bowl. Add the hot water and let stand for about 10 minutes until the noodles have softened. Drain and set aside.
Pour the noodles into a large platter and pour the palabok sauce over it. Add the pork and shrimp mixture to the top and sprinkle over the top, tinapa and sitcharon. Garnish the top with slices of eggs, celery leaves, green onion and calamansi halves. Serve hot with patis.