In a mixing bowl, combine the cubed chicken thighs, eggs, 2 tablespoons of cornstarch, and soy sauce. Mix well and set aside.
Whisk together the all-purpose flour and the rest of the cornstarch and add them into the bowl marinated chicken. Combine well. Chicken pieces should be covered with sticky batter.
Fill a deep frying pan up to about 1 inch deep with canola oil and heat to 375 degrees Fahrenheit. Fry for about 2-3 minutes and remove from oil. Place chicken on drying rack for about 5 minutes. Fry the chicken another time on high heat for another 2 minutes or until golden brown and fully cooked. Remove from oil and let cool on a drying rack.
To make the sauce mixture, in a mixing bowl, combine the orange juice, orange zest, low-sodium soy sauce, rice vinegar, brown sugar, sambal oelek chilli sauce, 7 tbsp of water, and garlic until well mixed and the brown sugar is well dissolved.
To make the cornstarch slurry, combine 1 tbsp of cornstarch with 2 tbsp of water in a small bowl and mix well until there are no more lumps in the mixture. Set aside.
Pour sauce mixture into a pan and heat over medium high heat. Once the sauce boils, add the cornstarch slurry while stirring the sauce continuously, making sure to break any lumps that may form. Let sauce come back to a boil and thicken, and remove from heat. If the sauce becomes too thick, add one tablespoon of water at a time to thin the sauce until you reach the desired consistency.
Place fried chicken pieces in a large mixing bowl, and pour the orange sauce over the chicken. Toss until every piece of fried chicken is coated with the sauce and top with chopped green onions.