Soak the clams in water for 30 minutes to remove any sand or debris. Rinse thoroughly with water and drain.
Mix all the ingredients for the dressing in a bowl and set aside.
Bring a large pot of water to boil and add the clams. Cook until the clams open up, then remove from the pot and soak into cold water. Cook the cloud ear fungus in a pot of boiling water until tender, then drain and set aside.
Combine the cooked clams, cloud ear fungus, and julienned cucumber in a mixing bowl. Add the dressing and toss to coat evenly.
Garnish with cilantro stems and sesame seeds before serving.
Tips:
Adding salt to the water when soaking the clams can help remove sand from their shells.