Soak rice noodles in warm water according to the package, usually 20–30 minutes, until bendable but still firm in the center. Drain thoroughly. Different noodle brands hydrate at different rates; do not boil them fully soft before stir-frying. Mix tamarind puree, fish sauce, sugar and 3 tablespoons water until dissolved.

Set all ingredients beside the stove. Heat 1 tablespoon oil in a large wok or 12-inch skillet over medium-high heat. Stir-fry chicken in two batches, 3–5 minutes each, until the thickest pieces reach 165°F (74°C). Transfer to a clean bowl.

Add remaining oil and garlic; stir 20 seconds. Push aside, add eggs and scramble just until set. Add drained noodles and sauce. Toss with two spatulas for 2–4 minutes, lifting rather than crushing the strands.

If noodles remain firm after the sauce is absorbed, add water 1 tablespoon at a time and toss another minute. Stop once tender and flexible with a slight chew. Avoid pouring in a large amount of water, which makes the bottom mushy.

Return chicken. Add bean sprouts and scallions and toss 1–2 minutes until sprouts are heated through and the chicken is hot. Divide immediately among four bowls. Scatter peanuts on top and serve lime wedges and optional chili flakes separately.