Gratin of vegetables with tuna

Preparation time: 30 minutes
Cooking time: 30 minutes
Ingredients (for 3 people): 

- A can of tuna in brine of 150 g
- 2 heaped tablespoons of flour
- 20 g butter
- 1 / 4 liter of milk
- 100 g grated cheese
- 1 egg
- 4 tomatoes
- 2 shallots
- 150 g mushrooms
- 2 zucchini
- Olive oil
- Salt and pepper
preparation:
Mince the shallots and fry in olive oil.
Add the chopped tomatoes.
Reduce.
Add salt and pepper.
Wash and cut mushrooms and zucchini, cook in salted water.
Drain and set aside.
Prepare a bechamel sauce with butter, flour, milk.
Add last Gruyère and egg yolk.
Add salt and pepper.
In a baking dish, place in layers tomatoes, mushrooms and zucchini.
Finish with coarsely crumbled tuna and white sauce.
Broil in the oven and serve hot.
the choice of vegetables can vary according to season: leek, broccoli, bell pepper .... but always keep the basic tomato.