in large nonstick pan, heat oil over medium high heat. add onion and garlic and saute until onion is soft, about 6-7 minutes. add fennel and continue to cook until fennel is tender crisp, about 4-5 minutes. add potatoes and carrots. continue cooking.
whisk together chicken broth and tomato paste and add to pan along with orange peel. simmer 10 minutes, covered.
place cod fillets on top of vegetables. cover pan and cook 10 minutes longer or until fish is cooked throughout. to serve, garnish with fennel fonds.