Cook the rice: Combine the rinsed long-grain white rice and the water in a medium saucepan, bring to a boil over high heat, then reduce to low, cover, and simmer until tender, 15–18 minutes. Remove from heat, rest 10 minutes covered, then spread on a sheet pan to cool. Refrigerate uncovered until thoroughly chilled and dry on the surface, at least 4 hours or up to 24 hours.
Beat the large eggs with the kosher salt in a small bowl and set aside. Have the chicken, garlic, ginger, soy sauce, ground white pepper, MSG (if using), scallions, toasted sesame oil, and chilled rice ready by the stove.
Heat a wok or large heavy skillet over high heat until lightly smoking. Add the vegetable oil (3 tbsp total); use about 1 tbsp to cook the eggs, 1 tbsp to sear the chicken, and reserve 1 tbsp for the aromatics and rice.
Pour in the beaten eggs and scramble just until softly set, 30–60 seconds. Transfer the eggs to a bowl.
Add about 1 tbsp of the oil to the hot wok. Add the chicken and stir-fry until browned at the edges and cooked through, 4–6 minutes. Transfer to the bowl with the eggs.
Add the remaining oil to the wok. Add the garlic and ginger and stir-fry until fragrant, 20–30 seconds.
Add the chilled rice, breaking up clumps; stir-fry until hot and lightly toasted in spots, 3–5 minutes. Drizzle in the soy sauce around the edges of the pan and toss to coat. Season with the ground white pepper and the MSG (if using). Return the chicken and eggs to the wok and stir-fry until everything is steaming and evenly combined, 1–2 minutes.
Off the heat, pour in the toasted sesame oil and add the scallions. Toss well, taste, and adjust with a splash more soy sauce if needed. Serve immediately.