Preheat oven to 400°F.
1. In a medium-size shallow dish, add 2 tbsp soy sauce. Place the chicken breasts in the soy sauce and turn to coat both sides. Set aside.
2. In a large ziplock plastic bag, add sesame seeds, flour, pepper, and garlic powder. Add chicken and shake to coat.
3. Spray a baking dish with nonstick cooking spray. Place the chicken in the dish. Lightly spray the top of each chicken breast with cooking spray. Bake for 25 to 30 minutes or until cooked through.
4. In a small bowl, combine remaining 2 tbsp soy sauce, lemon juice, vinegar, sugar, ketchup, water, and cornstarch. Mix well. Set aside.
5. Place a small saucepan over medium-high heat and add canola oil. When oil is hot, add onions. Sauté 1 minute. Add prepared soy sauce mixture and stir with a wire whisk for 1 minute or until thickened and heated through.
6. Spoon sauce over chicken breasts and serve with hot rice.
Makes 4 servings.