Heat peanut oil in a nonstick skillet over medium high heat until warm. Add raw peanuts and turn down to medium heat. Stir occasionally, until the peanuts turn brown and have a nice nutty aroma. Transfer the peanuts to a plate lined with several layers of paper towel to cool. Save the rest of the oil in the skillet for later use.

Cut chicken breast into 1 to 1.5 cm (1/2 inch) cubes and transfer to a bowl. Add 1 tablespoon light soy sauce and mix well. Add 2 teaspoons cornstarch. Mix by hand until the chicken is evenly coated with a thin layer of starch. Set aside.

Combine the remaining 1 tablespoon light soy sauce, Chinkiang vinegar, sugar, chili garlic sauce, and the remaining 1 teaspoon cornstarch to a small bowl. Mix well.

Cut and prepare the rest of the veggies.

Heat the same nonstick skillet again, over medium high heat. If there is not enough oil to cover the bottom of the skillet, add a bit more. When the oil is hot, spread the chicken across the skillet without overlapping the . Let it cook without stirring for 20 seconds. Flip to cook the other side for another 20 seconds. Stir a few times until all surfaces are cooked and slightly browned, but the inside is still raw.

Add the scallion and stir another few times. Mix the kung pao sauce again and pour it over the chicken. Immediately stir a few times to mix well until the sauce thickens, 20 seconds. Stop heat. Add peanuts and cucumber. Give it one last stir to mix well. Transfer everything to a plate.

Serve warm over steamed rice.