Prepare the dashi. In a saucepan bring to a boil some water (500-700ml will do), salt and kombu. As soon as the water starts boiling turn the heat off and let it cool completely.
Prepare the veggies. Slice the potatoes (peeled) and the courgette, and finely chop the onion, the tomatoes, the parsley and the garlic.
Assembling. In two monoportion oven safe casseroles dishes (or in one that serves two) start layering the dish. First goes olive oil, chopped onions, sliced potatoes, salt and pepper. Then a layer of sliced courgettes, garlic (both grated or finely chopped depending on your personal taste), half nori sheet teared in small pieces, salt and pepper. Then goes a layer of rice, followed by half chopped tomatoes, half of the parsley, onion, garlic and, once again, nori sheet. Finish with some olive oil, then cover with another layer of sliced potatoes. Spread the other half of tomatoes and parsley, season with salt and pepper and grate a generous amount of vegan cheese (or nutritional yeast).
From the side of the casserole, pour as much “dashi” broth as required to fill the tray right below the top layer of potatoes.
Bake in a 200°C (390°F) preheated for 45 minutes up to 1 hour. After the first 30 minutes check the amount of water and refill the casserole with some additional dashi if the rice has already absorbed all the liquid.