In a large mixing bowl, combine the finely chopped yellow onion, red bell pepper, minced garlic, grated ginger, chopped mushrooms, shredded or chopped cabbage, and chopped scallions. Add the roasted sesame seeds, soy sauce, roasted sesame oil, sugar, and panko breadcrumbs. Mix everything thoroughly until well combined.
Dust your surface with all-purpose flour to prevent sticking. Take a gyoza or wonton wrapper and place about a tablespoon of the vegetable filling in the center. Using your finger or a brush, moisten the edges of the wrapper with water. Fold the wrapper over to create a half-moon shape, pressing the edges to seal. You can create pleats along the edge for an authentic look if desired. Repeat with the remaining wrappers and filling.
Heat a large skillet over medium heat and add a tablespoon of canola oil. Once the oil is hot, carefully place the potstickers in the skillet, making sure they are not overcrowded. Cook for about 2-3 minutes or until the bottoms are golden brown.
After the bottoms are browned, carefully add about 1/4 cup of water to the skillet and immediately cover it with a lid. Allow the potstickers to steam for about 5-7 minutes or until the water has evaporated and the potstickers are cooked through.
While the potstickers are cooking, whisk together rice vinegar, soy sauce, honey, chili garlic sauce, sesame oil, minced green onion, and minced ginger in a small bowl. If you want a touch of brightness, add the freshly grated orange zest.
Remove the potstickers from the skillet and serve them hot with the dipping sauce on the side. Enjoy the crunchy, savory goodness of these delightful vegetable potstickers!