This is the sauce. Use half for marinade.
1. Simmer sauce until thick
2. Brown chicken fast in wok with the ginger, scallions, garlic and red chilies.
3.  Then add a chopped red pepper, half a chopped onion and half a chopped zucchini.
4. Then add sauce and 1 small can of diced water chestnuts and a handful of unsalted dry-roasted peanuts.
5.  Before serving, drizzle with 1 tsp sesame oil (don’t cook sesame oil, add it before serving)   

MAKE THIS SAUCE AHEAD OF TIME AND LET IT SIMMER UNTIL THICK
Combine in saucepan:
2 teaspoons vegetable oil 
1/2 teaspoon ground Sichuan pepper (Sichuan pepper is the powder you have
                                                                    after you roast and grind the peppercorns.)
8 to 10 dried red chilies
3 scallions, white and green parts separated, thinly sliced
2 garlic cloves, minced
1 teaspoon minced or grated fresh ginger
Saute these together to develop flavor, then add

1 tablespoon Chinese black vinegar, or substitute good-quality balsamic vinegar
1 teaspoon soy sauce
1 teaspoon hoisin sauce
2 teaspoons sugar
1 teaspoon cornstarch dissolved in 1 teaspoon water

Simmer sauce over medium heat until it thickens. Set aside to add at the end.

This recipe from https://www.epicurious.com/recipes/food/views/kung-pao-chicken-51179600