Bring a large pot of water to a boil. Cook rice noodles for 4-6 minutes until tender but slightly chewy. Drain and rinse under cold water to stop cooking and prevent sticking.

While noodles cook, slice vegetables into bite-sized pieces and cut protein into uniform pieces. Measure out sauce ingredients.

Heat 1 tablespoon oil in a large skillet or wok over medium-high heat. Cook protein until fully cooked through (chicken: 6-8 minutes, shrimp: 3-4 minutes, tofu: 5-7 minutes). Remove and set aside.

If using eggs, scramble them in the same skillet until just set. Remove and set aside with protein.

Add remaining tablespoon of oil to skillet. Saute minced garlic and grated ginger for 30 seconds until fragrant, watching carefully to avoid burning.

Add chopped vegetables to skillet. Stir-fry for 3-5 minutes until bright and tender-crisp, keeping heat high and vegetables moving.

In a small bowl, whisk together soy sauce, sesame oil, peanut butter, and rice vinegar until smooth.

Return cooked protein and eggs (if using) to skillet. Add drained noodles and pour sauce over everything. Toss until well combined, adding a splash of water if sauce is too thick.

Stir-fry everything together for 2-3 minutes until heated through and well coated. Serve hot, garnished with sesame seeds, green onions, and roasted nuts if desired.