Boil the potatoes: Place the halved baby potatoes in a large pot and fill with water. Cover and bring to a boil over high heat. Once boiling, reduce the heat to a simmer. Cook for 8-10 minutes or until just tender. Strain, then rinse with cool water.
Place the potatoes in a large bowl with the cilantro, green onion, and sesame seeds.
In a small bowl, whisk together the remaining ingredients. Stir in a splash or more of water to thin the sauce to a pourable consistency. Pour the sauce over the potatoes, then stir gently to combine all ingredients and coat the potatoes.