In a medium bowl, combine the raw chicken, spinach, garlic, soy sauce, and a pinch of black pepper.To assemble, spoon 1 tablespoon of filling onto each wrapper. Brush water around the edges of the wrapper. Fold the edges of the wrapper up and around the filling and pinch in the center to seal. Repeat with the remaining wrappers. Place the sesame seeds in a shallow bowl. Brush the bottoms of the dumplings with water and then dredge them in the sesame seeds. *vegetarian mushroom filling in the notes.To make the broth. Melt together 2 tablespoons butter and the onions in a large skillet over medium-high heat. Cook, stirring occasionally until softened, about 10 minutes. At this point, you'll want to slowly add the wine, 1/4 cup at a time, until the wine cooks into the onions. Continue to cook another 10 minutes until you've used all wine and the onions are deeply caramelized. Add 1 tablespoon butter, and season with chili flakes and pepper. Add the broth, soy sauce, bay leaf, and star anise. Simmer over low heat, 10 minutes. Meanwhile, heat a few tablespoons of oil in a large skillet set over medium heat. Add the dumplings and cook until the bottoms are golden brown, about 2-3 minutes. Carefully pour 1/4 cup of water into the skillet, it will splatter, so stand back. Immediately cover with a tight-fitting lid. Turn the heat to medium-low and let the dumplings steam for 5-6 minutes. Remove the dumplings from the skillet to a plate.Arrange the dumplings in shallow bowls. Ladle the steaming broth and onions over top. Top with green onions. Enjoy!