Bring a pot of water to a boil, salt it, add the noodles and cook until al dente. Drain.
While the pasta is working, in a large skillet, heat the oil, 3 turns of the pan, over high heat until smoking. Pat the ground beef dry with a paper towel, then crumble it into the hot oil.
Add the onion, chile, garlic, ginger, Szechuan pepper and five-spice powder to the beef. Stir-fry until the onion is slightly softened, 2 minutes.
Add the drained noodles to the beef mixture. Stir in the tamari (or liquid amino). Remove from the heat and toss with the lettuce and scallions. Serve with the chili oil (or sriracha).