Play around with different types of mushrooms in this pad Thai: In summer, try buttery-sweet chanterelles. In the spring, you can splurge for a few morels. Slideshow: Thai Recipes
Put the noodles in a large bowl and cover with very hot water. Let soak until just pliable, about 15 minutes (or according to package directions). Drain the noodles in a colander, shaking off any excess water.
Meanwhile, in a small bowl, whisk the soy sauce with the brown sugar, tamarind paste and Sriracha.
In a large nonstick wok or skillet, heat the oil until shimmering. Add the shallots and mushrooms and cook over high heat, stirring occasionally, until lightly browned, about 5 minutes. Add the garlic and carrots and stir-fry until soft, about 2 minutes. Add the noodles and the 4 scallions and stir-fry until heated through, about 2 minutes.
Scrape the noodles to one side of the pan and add the eggs. Cook, stirring occasionally, until nearly set, about 1 minute. Toss everything together. Add the sauce and stir-fry until the noodles are evenly coated and the sauce has thickened slightly, 2 to 3 minutes. Transfer the pad Thai to a platter. Garnish with the bean sprouts and thinly sliced scallions, then serve.
Tamarind paste is available from Indian, Asian and Latin markets.
Nam Pla is everywhere. It's just Asian stir fry if it's soy sauce. Same with palm sugar, not brown. tsk tsk