In a medium to large bowl, toss the chicken pieces with 2 tablespoons of the canola oil, 1 1/2 teaspoons of kosher salt and 3/4 teaspoon of pepper.

In a wok, heat 2 tablespoons of the canola oil. Add half of the chicken and stir-fry over high heat until browned, about 3 minutes. Transfer the chicken to a plate. Repeat with the remaining chicken.

Heat the remaining 2 tablespoons of oil in the skillet. Add the lemongrass, onion and garlic and cook over high heat, stirring, until fragrant, 2 minutes. Add the sake and cook until slightly reduced, about 1 minute. Add the oyster sauce, chili paste, scallions, dried chiles and jalapeño; bring to a boil. Add the chicken to the sauce and simmer until heated through, then serve.