For the vegetable lasagna from the steamer, brush the cooking tray with the olive oil. Place the first 6 lasagna sheets in it. Cover well with tomato sauce, spread vegetables on top and cover with mozzarella. Repeat this process 2 times and finally sprinkle the whole thing with grated Parmesan cheese. Cook for 35 minutes at 100° in the DG.
You can also prepare the lasagna a few hours before, then the cooking time is reduced to 20 minutes.