Soak the noodles. Place rice noodles in a large bowl and cover with very hot water. Soak 6–10 minutes, until just pliable but not fully soft.
Drain and toss with a little oil to prevent sticking.
Mix the sauce. In a small bowl, whisk tamarind paste, soy sauce, sugar, lime juice, chili paste, and rice vinegar. Taste and adjust: add sugar for sweetness, lime for brightness, or soy for saltiness.
Prep the tofu. Press tofu for 10–15 minutes to remove excess moisture, then cut into small cubes. Pat dry to help it crisp.
Cook the tofu. Heat 1 tbsp oil in a large nonstick skillet or wok over medium-high heat.
Add tofu and cook, turning occasionally, until golden on most sides, about 6–8 minutes. Remove and set aside.
Sauté aromatics and veggies. In the same pan, add remaining oil. Add garlic and onion (or scallions) and sauté 30–60 seconds until fragrant.
Add carrot and red pepper; stir-fry 2–3 minutes until just tender-crisp.
Add noodles and sauce. Add drained noodles and the sauce. Toss gently over medium heat for 1–2 minutes until the noodles absorb the sauce. If the pan looks dry, add a splash of water to loosen.
Fold in tofu and sprouts. Return tofu to the pan and add bean sprouts.
Toss for 30–60 seconds to warm through without losing crunch.
Finish and serve. Remove from heat. Stir in cilantro. Plate and top with peanuts, extra sprouts, scallions, more cilantro, and lime wedges.
Add chili to taste.