Moambé or Nyembwe Sauce is made by boiling the palm nuts fruits and discarding the skin and nut kernels.
Bring several cups of water to a boil in a saucepan. Place the palm nuts in the boiling water (they do not need to be covered by the water). Cover and cook the palm nuts for a few minutes, until the skins begin to come off.
Drain the water from the pan. Use a potato masher (or a mortar and pestle) to crush the palm nuts into a pulp.
Combine the palm nut pulp with one to two quarts (approximately one to two liters) of cold water. Stir. Squeeze the palm nuts with your hands to remove all the fruit and oil from the palm nuts.
Press the pulp through a strainer into the saucepan (rinse it first). Discard the nut skins and kernels that remain in the strainer. You might want to strain it twice, to remove all the nut kernels and bits of skin, and to make sure all the oil and fruit end up in the saucepan. Heat the pulp to a low boil, stir often, and cook until the sauce is thickened, maybe an hour.