In a medium bowl, whisk together the cornstarch, baking soda, vegetable oil, and soy or Tamari sauce. Add the cubed chicken, and toss with a spatula to coat. Set aside for 5-10 minutes.
In a 12-inch skillet, heat a tablespoon of vegetable oil over medium heat. When the oil is hot, pour in the beaten eggs, and let them cook, undisturbed, until they are done on the underside -- about 30 seconds. Flip and cook until done -- about 15 seconds. Transfer this omelet to a plate or heat-proof cutting, and set aside.
Add two tablespoons oil to the skillet. When the oil is hot, add the chicken. Sauté until brown on all sides -- 1-2 minutes. Use a spatula to push the chicken to one side of the skillet.
If the skillet is dry, add another tablespoon or two of the oil. Then add the onion, peas and carrots, and the garlic paste. Sauté until the onion is translucent and peas and carrots are hot -- about 2 minutes. (If you are using minced garlic, add it during the last 30 seconds of cooking time.) Transfer the chicken and vegetables to a pie plate and set aside.
If the skillet is dry, add more oil -- a tablespoon or slightly more. Then add the cooked rice and the soy or Tamari sauce. Stir and stir until every grain of rice absorbs the soy sauce and turns amber in color (there should be no white grains) -- 1 or 2 minutes.
Return the chicken and vegetables to the skillet, and stir them into the rice. Off heat, stir in the sesame oil. Use a knife or pastry cutter to cut the eggs into squares or rectangles, and then fold them into the rice and vegetables.
Divide the works among two bowls. Garnish each serving with the sliced scallion. Eat with chopsticks if you are on a diet. Otherwise, consume by spoon or fork!