Fish with tahini

This Lebanese dish is most often prepared with whole fish but you can also use leftover fish.

Put the tahini in a mixing bowl and gradually stir in the water and lemon juice until you have a pale liquid the consistency of a thin, creamy soup. Add a little more water if it looks too thick.
Pour a little vegetable oil into a frying pan over a medium heat, add the onions and fry until golden. Add the tahini and salt to taste, then allow to bubble until you see a little oil rising. Turn off the heat and slip the fish gently into the sauce. Serve tepid or at room temperature.