In a mixing bowl, mix together the smooth peanut butter, hot water, soy sauce, rice wine vinegar, cornstarch, and sugar. Mix well.
In a pan, cook the garlic with oil until soft and fragrant. Add the peanut butter mixture into the pan and stir until it reaches a slightly thicker consistency. Add in the red pepper flakes and mix well. Remove sauce from heat and pour into a bowl. Set aside.
To make pork filling, combine the ground pork, soy sauce, sesame oil, rice wine vinegar, garlic, green onions, eggs, and salt and pepper in a mixing bowl.
To assemble dumplings, place half of a tablespoon of the pork filling at the center of the dumpling wrapper. Make sure you pinch gently but firmly to tightly seal the dumplings. Refer to How to Fold Dumplings section for step-by-step method to fold dumplings.
In a large saucepan, bring water to a boil. Put in the dumplings one by one and stir gently to prevent them from sticking. Once the dumplings float to the surface, let them boil for another 30 seconds. If the water starts to rise and overflow, add in some water. Remove from water using a slotted spoon to drain off excess water.
Place cooked dumplings on a plate and pour spicy peanut sauce evenly on the dumplings. Garnish with sesame seeds and green onions.