Gather all the ingredients. In a medium bowl, whisk together all the ingredients for the sauce.
Cut green onions into thin pieces, mince shiitake mushrooms, and cut the lotus root into ⅛ inch (6 mm) slices. Put them all in a large bowl.
Add the seasonings to the bowl and mix well with your hands until the mixture gets sticky.
On a slice of lotus root, put a teaspoon of the meat mixture and spread. Put another slice of lotus root on top and press down to make a sandwich. Continue with the rest of the mixture and lotus root slices.
In a large frying pan, heat ½ inch of oil on medium heat.
Coat the lotus root with potato starch (cornstarch) and shake off any excess starch.
When the oil is hot, gently place lotus root in the pan. Cook both sides until nicely browned. When the meat is cooked thoroughly, transfer it to a paper towel to drain excess oil.
Meanwhile, in a small saucepan/frying pan, add all the ingredients for the sauce and cook on medium-low heat. In a small bowl, combine the starch and water and mix well. When the sauce is simmering, add the mixture to the pan and mix quickly and thoroughly. Turn off the heat and set aside until you are done with deep frying.
Reheat the sauce just before you serve. Pour the sauce over the lotus root and serve immediately.
You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days and in the freezer for a month.