Sauté all vegetables one by one in a large frying pan with 2 tablespoon of olive oil, starting with the onion then adding celery, carrot, zucchini, eggplant and leek. Season with salt and pepper and cook for a further few minutes. Set aside to cool.
Now add a little oil to the pan and sear the salmon on both sides. Season and set aside.
To assemble the lasagne, spread a layer of béchamel on the bottom of a rectangular baking dish then cover with lasagne sheets.
Add another layer of béchamel then a little salmon and vegetables, then Pesto Genovese on top. Repeat this process four times.
Bake the lasagne in pre-heated oven for 20-30 minutes. Allow to rest for five minutes before serving
To make the Bechamel:
Gently bring milk to the boil.
In a separate saucepan, gently melt the butter. Add flour and cook over low heat for a few minutes
Once milk is boiling, transfer a little at a time to the butter mixture, continuously whisking to prevent lumps.
Bring mixture to the boil and stir continuously. Simmer for 10 minutes and adjust seasoning if desired