In a large pot over medium-high, bring 6 quarts water to a boil. Meanwhile, in an 8-inch skillet over medium, toast the sesame seeds, stirring often, until lightly browned, 2 to 3 minutes. Cool completely. In an electric spice grinder or in a mortar with a pestle, coarsely grind 2 tablespoons of the seeds; reserve the remainder for garnish. Transfer the ground seeds to a medium bowl, then stir in the soy sauce, sesame oil and garlic; set aside.