Cut the 3 fennel bulbs into thin strips. Chop the fennel greens and set them aside.
Heat olive oil in a pan over medium-high heat. Fry the fennel strips for 5 minutes.
Cut the onion into half rings. Add the onion and chopped garlic to the pan. Season with salt, pepper, and 1 tablespoon sugar. Cook for 5-10 minutes until the fennel is golden yellow and tender.
Sprinkle the chopped fennel greens on top and serve.