Sauté the mushrooms, seasoned, in a couple of tablespoons olive oil the moment they have been juliènned, over a high flame until their liquid is evaporated. Squeeze in a few drops of lemon juice.
Stew the tomatoes, seasoned, in
Cut the eggplant into slices of from
Spread the mushrooms in the bottom of an oiled gratin dish, arrange half of the eggplant slices on this bed, spread them with the stewed tomato mixture, and arrange the remaining eggplant slices on top. Beat the eggs with a whisk, whisk in the milk, salting lightly, then the dissolved saffron, and pour over the vegetables, lifting them gently here and there around the sides with a fork, permitting the liquid to penetrate evenly. Bake for about 30 minutes in a medium (375°) oven or until the custard has only just set in the center.