In a small bowl, combine rice vinegar and serrano and let sit at room temp for at least 15 minutes.
Combine chicken with 2 tablespoons water and baking soda in a bowl. Let sit at room temperature for 15 minutes. Rinse chicken in cold water and drain well.
Meanwhile, bring 6 cups water to a boil. Place noodles in a large bowl. Pour boiling water over noodles, stir, and let soak until noodles are almost tender, about 8 minutes. Stir halfway through the soaking time. Drain and then rinse with cold water. Drain well and toss with 2 teaspoons vegetable oil.
In a small bowl, mix together oyster sauce, soy sauce, sugar, vinegar, molasses, and fish sauce. Set aside.
In a 12-inch nonstick skillet, heat 2 teaspoons oil over high heat. Add garlic and cook, stirring occasionally, for 1 to 2 minutes. Careful not to burn garlic, but you do want it to turn golden brown.
Add chicken and 2 tablespoons sauce mixture. Spread chicken out in an even layer. Let chicken cook without stirring for 1 to 1 ½ minutes, until it begins to brown. Use tongs to turn chicken and continue to cook without disturbing until second side is browned, about 1 to 1 ½ minutes. Push chicken to 1 side of skillet.
Add 2 teaspoons oil to empty side and then add eggs. Gently stir eggs using a rubber spatula until eggs start to set. Stir eggs and chicken mixture together, breaking eggs into pieces. Continue cooking for 30 to 60 seconds, or until eggs are fully cooked. Transfer mixture to a bowl.
Place 2 teaspoons oil in the now empty skillet and heat over high heat until smoking. Add broccolini and 2 tablespoons sauce. Toss to coat. Cover skillet and cook for 2 minutes, stirring halfway. Uncover and continue to cook 2 to 3 minutes, until broccolini is very brown in spots, stirring just once. Place broccolini in bowl with chicken mixture.
Heat another 2 teaspoons oil in skillet and add half of noodles and 2 tablespoons sauce and toss to coat. Cook for about 2 minutes, until noodles start browning in spots, stirring just once. Place in the bowl with chicken mixture. Repeat with remaining 2 teaspoons oil, noodles, and sauce. When second batch of noodles is starting to brown, add all of the contents back to skillet and toss to combine. Leave alone to cook for a final 1 to 1 ½ minutes. Serve immediately with chili vinegar as a condiment.