You make to brown the onion, the celery and the carrot in 8 spoonfuls of water. You add the mushrooms, and after having let them cook for three minutes, you add the preserve of tomato loosened in eight teaspoons of water. Leave them to you to cook until when they don't become well tender. Apart you dissolve the flour in the milk, in a little pan, salty and mixing without interruption until the batter it doesn't become dense. Out fire incorporated the grated cheese and the margarine and you pour a half this sauce in the mixture of stewed vegetables, amalgamate well and you fill with this farcitura the cannelloni, that you will prepare in an oven baking-pan of anti-adherent material . Cover you them with the other halves bechamel to the tomato and bake them to you to 180°C. They will be ready when the surface will be gilded.