Start by mixing all ingredients of sauce in a bowl. Also, boil spaghetti 1 minute less than the instructions on the packet. Then transfer spaghetti to the colander and drain the liquid. Wash spaghetti with cold water while still in the colander to stop cooking. Then apply few drops of oil all over the spaghetti and let it cool. Set aside.
Take 2 tablespoons of sauce and mix with the chicken. Mix well and marinate chicken for 20 minutes.
Fry garlic and chilis to season the oil. (You can use any dry or fresh whole red chilies.)
Add chicken and stir-fry for 3-4 minutes on high heat until cooked.
Stir in veggies except for green onions and continue to stir fry for 2 minutes until soft.
Mix in the prepared sauce too.
Add noodles and mix well with a noodle spoon. Continue to stir fry for 2-3 minutes.
Finally, sprinkle green onion. Mix well and serve Desi Chow mein.