In a large mixing bowl, combine the chicken thighs, ¼ cup of water, baking soda, and salt. Mix vigorously until the chicken mostly absorbs the water.

Add the eggs and mix well again. Next, incorporate the cornstarch and blend until evenly distributed.

Finally, add the oil and mix until combined.

In a wok or tall pan, pour in about 2 to 3 inches of oil and heat it to 375°F.

Carefully add the marinated chicken pieces one by one, ensuring not to overcrowd the pan. Fry the chicken pieces for about 4 to 5 minutes, then remove and drain for 2 to 3 minutes.

Bring the oil back to 375°F and fry the chicken again for an additional 5 to 6 minutes or until golden brown and crispy.

While the oil heats, whisk together the ketchup, water, sugar, vinegar, cornstarch, soy sauce, and dark soy sauce in a bowl. Set aside.

Add a small amount of oil to a clean wok or pan over medium heat. Toss in the white parts of the green onions and stir-fry for about 10 seconds until fragrant.

Pour the prepared sauce into the pan and increase the heat to medium-high. Stir frequently until the sauce bubbles and thickens.

Once the sauce has thickened, toss the crispy chicken pieces in the wok until thoroughly coated.

Serve immediately with white or fried rice, garnished with toasted sesame seeds and the greens of the sliced green onion.