Bring a large pot of salted water to a boil and cook the noodles according to package directions (about 8 minutes). Drain, rinse under cold water, shaking off excess. Set aside.
Set a large skillet or wok over high heat. Turn on your hood or vent fan. When the pan is hot, add 1 tablespoon of the oil and swirl it around. When the oil starts to smoke, add half of the garlic, take the wok off the heat, and sizzle the garlic in the wok until fragrant and just starting to turn golden, about 15 seconds.
Add the turkey and stir to break it up and coat it in the oil. Return the wok to the heat, and cook the turkey, stirring constantly, for about 1 minute. Add 1 teaspoon of the fish sauce and 1 teaspoon of sugar and cook, stirring, until the meat is just cooked through, 2 to 3 minutes.
Transfer turkey to a bowl, wipe out the wok, and return it to high heat. Add the remaining tablespoon of oil, swirl to coat the pan, and when the oil smokes, add the pale green and white parts of the scallions and cook, stirring, for about 1 minute, until softened. Add the snap peas, stirring to coat in the oil. Let it sit for 30 seconds or so before starting to stir and toss it. Add 1 teaspoon fish sauce and 1 teaspoon sugar and cook for another 3 to 4 minutes, until bright green and tender. Stir in 1 to 2 tablespoons water if the vegetables are sticking to the pan.
Add the rest of the garlic, the noodles, and the remaining fish sauce and stir to combine with the peas. Toss and stir to mix all of the ingredients together and cook until the noodles are warmed through. Add the turkey, soy sauce, and remaining teaspoon of sugar and stir to combine. Cook for another 30 seconds and remove from heat.
Transfer noodles to four bowls and sprinkle the lime juice over the noodles, followed by the crushed peanuts and the chopped scallion greens. Serve with extra limes and sriracha.