Prepare the ice water: fill a large bowl with cold water and then add the ice cubes. Place the bowl in the fridge 30 minutes before you start preparing the spinach salad. Add the sesame seeds to a blender (you can also use a mortar and pestle).
Blend the sesame for a good minute until it is very fine, more like flour.
Once cooled, gently squeeze the steamed spinach and chop it up roughly. Add it to a large bowl together with the blended sesame, fish sauce, soy sauce and a tablespoon of water. Season with a pinch of pepper and salt.
Stir the spinach salad. Then check the seasoning and add extra pepper, salt, fish sauce or soy sauce to taste if necessary. Serve cold.