To Make the Kung Pao Sauce:.
In a medium saucepan, whisk together the chicken stock and cornstarch until the cornstarch is fully dissolved. Stir in all the remaining sauce ingredients and bring to a boil over medium-high heat. Reduce the heat and simmer until the sauce is thick enough to coat the back of a spoon, 15 to 20 minutes. Set aside.
To Make Egg White-Cornstarch Mixture:
In a mixing bowl, use a whisk to stir together the egg whites, cornstarch, and salt until thoroughly blended; be careful not to beat them into a froth. Set aside.
To Prepare the Pasta:.
Bring a large pot of salted water to a rapid boil. Add the pasta and cook until al dente, 8 to 10 minutes.
Meanwhile, in a large nonstick frying pan over high heat, heat the olive oil for about 1 minute. Add the chicken pieces to the Egg White-Cornstarch Mixture and toss to coat them. Taking care to avoid splattering, add the coated chicken to the pan and cook like a solid pancake until the egg mixture sets; then, using a large spatula, carefully flip the chicken pieces over together and, with a wooden spoon, gently separate the pieces.
Gently stir the Chinese peppers and roasted peanuts into the pan. As soon as they darken in color, after no more than 1 minute, stir in the garlic and scallions. Once the garlic begins to brown, after no more than 30 seconds, add the Kung Pao Sauce and toss and stir to coat the ingredients.
When the pasta is ready, drain it well and, in a large mixing or serving bowl, toss it thoroughly with the sauce. Serve family-style or transfer to individual serving bowls, arranging the chicken, vegetables, and peppers.