Prepare Yeast Mixture: Dissolve dry yeast in lukewarm water with sugar, salt, and vegetable oil.
Make Dough: Add all-purpose flour to the yeast mixture and knead until smooth. Let it rise until doubled in size.
Prepare Vegetable Filling: Chop onion, carrot, and green onion, sprinkle with salt, and let sit to draw out moisture. Squeeze out excess water.
Prepare Pork Filling: Mix minced pork belly with minced garlic, soy sauce, sesame oil, and black pepper.
Combine Fillings: Combine vegetable and pork fillings. Adjust seasoning.
Sauté Filling: Sauté the filling mixture in vegetable oil, adding more sesame oil and black pepper. Cook for about 3 minutes.
Prepare Dumplings: Divide the dough and roll out into circles. Fill with the pork and vegetable mixture, then seal.
Steam Dumplings: Place dumplings in a steamer and let rise for 20 minutes. Steam until cooked through.