Heat sesame seeds in a small skillet over medium-high heat, stirring constantly, 3 minutes or just until toasted.
Microwave vinegar in a medium-size, microwave-safe glass bowl at HIGH 1 minute or just until hot. Add sugar, and whisk until dissolved. Add next 3 ingredients, toasted sesame seeds, and, if desired, poppy seeds; whisk until blended. Store in refrigerator up to 1 week.