Make the sauce: Over a low flame, heat the tamarind, fish sauce, and brown sugar together until the sugar is dissolved. Stir in the chili powder a teaspoon at a time to desired spiciness. Bring the sauce to a simmer. Turn off the heat (keep sauce warm).
Make the pad thai: [The key is to cook up 1-2 servings at a time!] Heat 2-3 tablespoons of oil in wok or large frying pan over high heat. Add 2 ounces of chicken and stir-fry until it is half cooked. Add 1-2 tablespoons of sauce, and a pinch of garlic. Stir around and add about 2 cups of loosely packed (for me, a big handful) of rice noodles plus 1/4 cup of sauce to the pan and stir vigorously until the noodles soften. If it dries out, you can add some water. Push the noodles to the side and crack an egg into the pan. Let the egg cook for 10 seconds and then toss the noodles and egg together in the pan. Drop 4-6 shrimp, a couple of tablespoons of ground peanuts, a heaping tablespoon of turnip, and 1/2 cup of sprouts into the pan. Stir fry until the shrimp are just cooked (very fast “ about a minute). Toss in the green onions or garlic chives and remove from heat. Serve hot with more sprouts, ground peanuts, and lime wedges for garnish.