Remove the tougher part from the asparagus, scrape them with a knife and once rinsed slice them, then clean the carrots and once diced toss them in a pan with plenty of salted water and blanch them for 3-4 minutes.Clean the celery and slice it finely and blanch it in boiling water. Chop the onion finely and soften it in a pan with oil and butter. Once drained add the carrots, the celery, the asparagus and a pinch of salt and pepper, cover the pan and simmer for 7-8 minutes.In the meanwhile cook the pasta in a pan with plenty of boiling salted water. Drain al dente and mix it with the vegetable sauce. Serve immediately.