Chop the sweet potato into bite size pieces and cover with some salt and olive oil.
Air Fry at 180°C for 20 minutes.
Meanwhile, soak the cashews in a small pot of boiling water, leaving to simmer for 10 minutes to soften.
Using Sauté on your Instant Pot or a frying pan, cook the mushrooms and onions in some oil. Cook for 5 minutes stirring regularly then add the tamari, ensuring all the mushrooms and onion get coated.
Add the carrot, garlic and the chilli, and cook for a further 3 minutes, stirring regularly.
Add the remaining ingredients for the tomato sauce, plus the cooked sweet potato. Bring to the boil, then reduce the heat and leave to simmer for 10 minutes. Taste and season with more salt and pepper to your taste and once it is finished, leave it to sit with the lid off while you make the cashew sauce.
Drain and rinse the soaked cashews, then blend these with the remaining cashew cream ingredients.
Assemble your lasagne in a baking dish. Start with a thin layer of the cashew cream across the bottom, then a layer of lasagne sheets. Add a half of the tomato sauce on top of the lasagne sheets and spread it so that it is level and compacted. Continue layering until you have use your ingredients, ensuring the last layer is the cashew cream again on top.