Prepare the brown rice noodles according to package instructions by soaking them in hot water until tender, then drain and set aside.
In a small mixing bowl, whisk together the tamari, lime juice, fish sauce, maple syrup, and red pepper flakes to create the sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat and sauté the minced garlic and shrimp until the shrimp are pink and opaque.
Push the shrimp to one side of the pan, crack the egg into the empty space, and scramble it quickly until just set.
Add the cooked noodles, bean sprouts, and half of the sliced scallions to the skillet, pouring the prepared sauce over the mixture.
Toss all ingredients together for 2 minutes until the sauce has thickened slightly and the noodles are evenly coated and heated through.
Serve the pad thai immediately, garnished with the remaining scallions and crushed peanuts for added crunch.