Cook the noodles: Boil according to package instructions until just shy of tender. Drain, rinse briefly under cool water to prevent sticking, and toss with a little oil.
Set aside.
Whisk the sauce: In a bowl, combine peanut butter, soy sauce, chili-garlic sauce, rice vinegar, brown sugar, and sesame oil. Add warm water a little at a time until smooth and pourable, like heavy cream.
Prep your add-ins: Slice vegetables and protein so everything cooks quickly. Keep ingredients in separate piles for easy stir-frying.
Heat the pan: Set a large skillet or wok over medium-high heat.
Add 1 tbsp oil until shimmering.
Cook the protein: Add chicken, shrimp, tofu, or tempeh. Season lightly with salt. Stir-fry until cooked through and browned in spots.
Transfer to a plate.
Sear the veggies: Add the remaining 1 tbsp oil. Stir-fry bell pepper, peas, carrot, and mushrooms for 2–3 minutes until crisp-tender.
Add aromatics: Push veggies to the sides. Add garlic and ginger to the center and cook 30 seconds until fragrant, stirring constantly to prevent burning.
Bring it together: Return protein to the pan.
Add cooked noodles and pour in the peanut sauce. Toss with tongs for 1–2 minutes until everything is coated and glossy.
Finish and taste: Add green onions. Taste and adjust with more soy for salt, lime or vinegar for brightness, or chili sauce for heat.
If too thick, splash in a bit of water.
Serve: Top with chopped peanuts, cilantro, sesame seeds, and a squeeze of lime. Serve hot.