Place the clams in a large bowl and rinse under cold, running water for 5 to 10 minutes to "spit" the clams of all sand and grit. Drain and set aside. In a small bowl, combine the dark soy, oyster sauce, lime juice, coconut palm sugar and half the black pepper. Set aside. Heat the oil in a large saute pan or skillet over high heat. Add the garlic, ginger and the remaining black pepper and cook for 2 minutes, stirring occasionally, to release the flavors, but do not let the garlic brown. Add the clams. Add 1/2 cup water and cover immediately to let the clams steam open. This will take 3 to 4 minutes. All the clams should be open, remove any that are not. Add the oyster sauce mixture. Stir well. Add the butter, stir well and pour out into a large bowl. Serve immediately with the fresh herbs sprinkled over the top, toasted bread and wedges of fresh lime to squeeze over the clams.