Place fish heads in a pot filled with ice and cover with water. Allow ice to melt and drain all water. Wash heads well and replace in pot with fresh water. (Water should appear clear.)

Add remaining broth ingredients and bring to boil. Lower fire and simmer over low flame for 15–20 minutes. (If the flame is too high, the natural gelatin of the broth will dissolve.) Strain with a fine strainer. Broth should be clear and delicate tasting.

Sauté onions and leek in olive oil over low flame until transparent. Add remaining vegetables and ginger. Cover pot and steam until all vegetables are soft.

Pour prepared broth into vegetables and bring to gentle boil. Add remaining seasonings and chickpeas. Continue cooking over low flame for 15–20 minutes.

Grill or fry fish until done. Arrange warm couscous on a plate. Pour a generous amount of fish-vegetable sauce on top and top with a slice of fish.