Spinach namul

Name: Spinach namul
Ingredients: 2 pounds spinach; 5 ice cubes; 1 tablespoon soy sauce; 1 teaspoon sesame oil; 1 teaspoon crushed and roasted sesame seeds, plus additional for garnish; 1 clove garlic, minced; 1 teaspoon rice wine vinegar; 1 ½ teaspoons minced green onion; 1 teaspoon sugar (white or brown)