Japanese Clear Clam Soup (Ushiojiru)

Bahan-bahan (4 porsi)

• 1 lb manila clams ((16–20 pieces))
• 4 cups water
• 1 kombu (dried kelp) ((2 x 2 inches, 5 x 5 cm))
• 1 Tbsp sake
• ⅛ tsp Diamond Crystal kosher salt
• 2 –3 sprigs mitsuba (Japanese parsley) ((for garnish))