Preheat the oven to 400°F.
In a medium bowl, stir together the coconut milk, red curry paste, garlic, ginger, soy sauce, rice vinegar, and sesame oil until well combined. Add the bok choy and toss lightly to coat.
Pour half the sauce into a 9x13-inch casserole dish. Arrange the frozen dumplings in an even layer over the sauce. Pour the remaining sauce evenly over the top.
Cover tightly with aluminum foil and bake for 25 minutes. Remove the foil and continue baking for an additional 15 minutes until the dumplings are heated through and the edges are lightly crisp.
Finish and serve. While the dumplings bake, combine the chopped cilantro, scallions, and toasted sesame seeds in a small bowl. Sprinkle evenly over the finished casserole and serve immediately.