Boil the Spaghetti (150 gram) according to package directions, but drain a minute early (reserve a little pasta water).
Add the Garlic (1 clove) and Arugula (50 gram) to a food processor, then blend into a fine paste.
Add the Avocado (1), Lemon Juice (2 tablespoon), and Olive Oil (1 tablespoon), to the food processor and blend again until smooth. Season with Salt (to taste) and Ground Black Pepper (to taste).
Drain the pasta and return to the pot. Add the sauce and cook over low heat for 5 minutes, stirring constantly. Add the pasta water a bit at a time if it seems too dry. Serve warm or chilled.