Soak pad thai / rice noodles in warm/hot water for 30-45 minutes, or according to package instruction. Drain water when soaking is completed.
Mix together tamarind concentrate, fish sauce, brown sugar and water to create Pad Thai sauce. (Important: Please see notes below)
Mince garlic and slice shallots, and thinly slice chicken.
Cook one serving of pad thai at a time. To cook the first serving, add 1 tbsp of vegetable oil into wok and let it heat up under high heat. Once wok and oil is heated, add 1 ½ tbsp. of minced garlic and 3 tbsp of minced shallots. Cook for 30-60 seconds, then add half of the sliced chicken prepared. Cook for a couple of minutes, or until chicken is mostly cooked.
Add half of the soaked & drained pad thai noodles, cook for a couple of minutes until noodles soften, stirring continuously.
Add ~3 tbsp of Pad Thai sauce, and 1 tsp of red pepper flakes (add more to make it spicier). Continue to stir.
Add ½ cup of bean sprouts, then move the noodles to one side of the pan, and crack an egg directly onto wok, break the egg yolk, and then cover the slightly raw egg with all the noodles. Mix everything together for a minute or so. Remove from heat.
Garnish with crushed peanuts, green onions, cilantro and lime.
Repeat Step 4-8 for the second serving. There might be a little bit of leftover Pad Thai sauce.
Serve and enjoy!