To make the batter, mix the flour, egg yolks and olive oil in a bowl, gradually adding the water, and beating until it is nicely smooth. Keep the whites on one side.
Poach the cod as explained in the recipe for brandade de morue, above. Flake it and pulse it in the food processor until finely chopped.
Heat the oil in a pan and soften the shallots and garlic until just ten