Mix the ketchup, brown sugar, fish sauce, oyster sauce, soy sauce, and rice vinegar in a bowl.
Chop all the other ingredients that have to be prepared.
Prepare the rice noodles according to the package instructions. In my case, I just poured boiling hot water on my rice noodles and strained it after 3 minutes.
Put olive oil in a deep pan, wait until hot, saute the onions, then the garlic.
Add the chicken, and saute until light brown.
Move the chicken to one side, and add the lightly whisked eggs on the other side. Once the eggs are cooked, mix together chicken and eggs.
Add the cooked rice noodles, then the pad thai sauce. Mix everything together.
Serve with green onions, walnuts, a sprinkle of cayenne pepper, and lemon wedges.