In a mixing bowl, combine the chicken pieces with the salt, lightly beaten egg, and corn starch. Mix well until the chicken is evenly coated.
In a large skillet or wok, heat the canola oil, vegetable oil, and sesame oil over medium-high heat.
Once the oil is hot, add the coated chicken pieces to the skillet. Cook for about 5-7 minutes until golden brown and cooked through.
In the same skillet, add the minced garlic and ginger. Sauté for about 30 seconds until fragrant.
Add the sliced baby portabello mushrooms to the skillet. Cook for about 5 minutes until tender.
Stir in the fresh green beans and cook for another 3-4 minutes until bright green and tender-crisp.
Return the cooked chicken to the skillet, pour in the soy sauce and balsamic vinegar, and toss everything together.