This was fantastic with sea bass, but not very photogenic, so this is a generic picture of fennel that I found on the web:
Ingredients2 tbs olive oil
1/2 bulb fennel
1 red sweet (bell) pepper
1 onion
Salt, pepper, other seasonings to taste - I used za'ataar and Dunn's River fish seasoning
Chop the vegetables, removing the white ribs and seeds from the pepper. Cook in the olive oil over a medium heat until they are cooked, stirring fairly frequently. This will take about 15-20 minutes. Transfer to a food processor and blitz until smooth, adding a bit of lemon juice if it is too dry. Serve with fish.