Remove the stalk from the dry red chilies. Cut the chilies lengthwise using a pair of scissors.
Remove their seeds.
Soak the chilies in boiling hot water for 30 minutes.
Drain the water and add the soaked chilies to a blender along with ¼ cup of water and blend to make a smooth paste.
Heat oil in a pan over high heat.
Once the oil is hot, add ginger, garlic, celery stalk, and onions and fry for 2-3 minutes.
Reduce the heat to medium. Add the chili paste along with ½ cup of water to the pan and cook for 10-12 minutes, stirring frequently.
Add soy sauce, vinegar, tomato ketchup, sugar, pepper powder, Ajinomoto, and salt, and cook for 5-6 minutes.
Remove the pan from the heat and let the sauce cool down to room temperature. Store the Schezwan sauce in a clean airtight container for upto 1 month in the refrigerator or for upto 6 months in the freezer.