Start by cleaning the asparagus: remove the ends, clean them with a potato peeler and slice them, leaving the tips intact. Steam them for at least 10 minutes. Pour a little olive oil into a frying pan, add the guanciale cut into strips and the finely chopped onion. Let it brown on a medium flame for a few minutes. Add the cooked asparagus, salt and pepper, and let everything brown with the lid ajar. Cook the stringozzi in plenty of salted water, then toss them in the pan and if necessary add a ladle of pasta cooking water. Sprinkle with pecorino cheese, a drizzle of oil and a pinch of black pepper: the dish is ready to be served.