Preheat oven to 400 degrees. Make the meatball mixture: combine all ingredients except for the sesame seeds and rice in a large bowl. Form the mixture into 12-14 meatballs. Place meatballs in a single layer onto a baking sheet lined with parchment paper. Bake 25-30 minutes.
While the meatballs are baking, make the sauce: Combine all ingredients except the cilantro in a small saucepan over medium-high heat. Bring the mixture to a boil, then reduce heat and simmer 10-15 minutes to thicken. Be sure to whisk the mixture occasionally.
Place the rice into bowls. Top with meatballs and plum sauce. Garnish with sesame seeds and additional cilantro.