In a large bowl, combine the first 8 ingredients (ground pork, soy sauce, cornstarch, ginger, sesame oil, oyster sauce, sugar, and beaten egg). Mix very well. Make a “claw” with your clean hands and stir it vigorously (and continuously) until mixture is pasty and the meat texture is stringy. Or, you can pick up the mixture with one hand and “slap” it a few times in the bowl.
Pat the shrimps and water chestnuts with paper towels again to make sure there’s no extra moisture. Then, add to the mixture followed by the green onions. Mix very well to combine.
Form a “cup” with one hand and place one wrapper on top. Add 1 tablespoon of the mixture in the middle and push the mixture towards the “hole” of your hand with a spoon. Gently squeeze the wrapper as you push it down (make sure the filling covers the top). Flatten bottom of siomai on the counter. Repeat with the rest. (see step-by-step photos below)
Top each siomai with a pinch of the minced carrots or one whole shrimp (or both).
Fill the steamer pot (bottom part) with an inch of water and bring water to a boil. Brush the steamer (where you’ll cook the siomai in) with oil then arrange siomai. Steam on medium for 15 minutes.
Carefully remove and serve with a mixture of ¼ cup soy sauce and the juice of half a big lemon or about 3-4 tablespoons of freshly squeezed calamansi juice.