Stir together cornstarch, salt and pepper in a medium bowl. Add chicken and toss to coat. Warm oil in a large nonstick skillet over medium high heat. Place chicken in skillet and cook, stirring, about 5 minutes, until lightly browned. With a slotted spoon, transfer chicken to a plate.
Return skillet to heat, add red onion and garlic and cook, stirring, until softened, about 3 minutes. Stir in cabbage, edamame and 1/2 cup water and cook, stirring, about 8 minutes, or until edamame are cooked through.
Stir in reserved chicken and hoisin sauce and cook, stirring, about 3 to 5 minutes, or until warmed through. Remove skillet from heat, stir in cilantro, and serve hot on top of rice.