Start by soaking the dried red chilies in warm water for about 10 minutes.
Heat oil in a pan over medium heat, and saute the ginger, garlic and chopped green onions for about 2-3 minutes.
Blend the dried red chilies in a blender jar (draining away the excess water) and add the mixture into the pan. Let this cook for about 3-5 minutes.
Now add the remaining ingredients and give it a good mix. Let it cook for another 2-3 minutes and then take it off heat. Let it cool down and serve or store for later.
Notes
To lend the Schezwan sauce that authentic Asian flavor, saute the aromatics in sesame oil.
Blend the chilies into a coarse paste instead of getting it smooth if you want the sauce to have a bit of a chunky texture.
To cut down the heat, you can de-seed the chilies before you soak them or blend them.
You can also add a pinch or MSG or Aromat powder to the sauce towards the end to enhance the flavor.
Make sure you cook the mixture on medium-low heat, or the ingredients may end up burning, and the sauce will have a bitter taste.