Cook the pasta according to the instructions on the package. Grate the asparagus and cut into pieces. Boil in salted water for about 3 minutes.
Cut the radishes into quarters and the onion into rings.
Brown the butter and add vinegar, 10 shredded sage leaves and finely grated lemon zest.
Turn the pasta around with the vegetables, spinach and the browned butter. Season with salt and pepper. Top the salad with the rest of the sage leaves.