Sauté onion in butter until soft.
Add fennel root and sauté; stir until it starts to brown.
Add chicken broth.
Simmer until tender and add radish, fennel herb and cream; reduce until it thickens.
Season and dust the Tilapia with flour, then sauté (in a separate pan) until golden brown.
Top with the fennel mixture.
Serve with pasta or rice.