Cook the pasta in salted water until al dente, drain and drain.
Squeeze the lemon. Remove the avocado from the skin. Cut the pulp into pieces and mix with the lemon juice. Peel and chop the garlic, mix finely with the avocado mixture and olive oil in a blender. If the mixture is too firm, add some of the pasta water. Season to taste with salt and pepper.
Cut the spring onion into rings, wash the tomatoes and cut in half.
Put the clarified butter in a pan, heat it and add the asparagus. Fry for about five minutes. Add the onion rings and fry for another two minutes. Season with salt and pepper. Add the tomato halves and just heat them up.
Mix the avocado cream and the asparagus-tomato mixture into the pasta and arrange on two plates.