Heat a large skillet over medium-high heat. Add a tablespoon of the vegetable oil, followed by the cubed chicken. Cook the chicken until it's no longer pink and fully cooked through. Once done, transfer the chicken to a separate dish and set it aside.

Using the same skillet, add another tablespoon of oil. Crack the eggs into a bowl, whisk them briefly, and then pour into the skillet. Stir and break apart the eggs as they cook. Once fully cooked, transfer them to the dish with the chicken.

Pour two more tablespoons of oil into the skillet. Add the diced onion and minced garlic, sautéing until they become fragrant and start to brown, roughly 2-3 minutes. Stir often to prevent burning. Then, add the green onions and cook for an additional 2 minutes until they're tender.

In a small bowl, mix together three tablespoons of brown sugar, three tablespoons of Thai fish sauce, two tablespoons of tamarind puree, one tablespoon of lime juice, a quarter teaspoon of ground cayenne pepper, two tablespoons of oil, and one tablespoon of water. Whisk these ingredients well to combine. Pour this sauce mixture into the skillet with the onions and garlic. Reduce the heat to a simmer, letting the sauce heat through.

Return the cooked chicken and eggs to the skillet. Add the cooked Thai rice noodles. Toss everything together to ensure the sauce evenly coats the noodles, chicken, and eggs. Cook for another 2-3 minutes, just until everything is heated through.

Serve the dish hot, garnished with dry roasted peanuts and optional chopped fresh cilantro for added flavor and freshness.