Whisk together stock, sherry, cornstarch, sugar, vinegar, salt, and pepper in a small bowl and set aside.
In a medium bowl, toss together chicken, cornstarch, sherry, salt, pepper and egg white. Let sit for 30 minutes and then drain.
Heat oil in a 14 inch flat-bottomed wok or high-sided skillet over medium-high heat until a deep-fry thermometer reads 300 degrees F. Add chicken and fry, stirring gently and constantly, until it turns white and is cooked through (45 seconds).
Using a slotted spoon, transfer chicken to a large colander and set over a bowl to drain. Heat oil to 350 degrees F. Add chanterelles to oil and fry, stirring often, until barely soft (30 seconds). Using a slotted spoon, transfer to colander with chicken to drain then set aside.
Discard all but 1 tbsp oil and return wok to high heat. Add scallions, chiles, garlic, and ginger and cook, stirring constantly, until fragrant (10 seconds).
Add sauce and cook, stirring constantly, until thickened (20 seconds). Return chicken and chanterelles to wok and toss with sauce until well coated.
Transfer to a serving platter, drizzle with sesame oil, and serve with rice.