Preheat the oven to 400ºF. To prepare the vegan ricotta, combine the tofu, lemon juice, salt, oregano, and basil in a food processor. Process until smooth, and set aside.
To prepare the Cashew Parmesan Sauce, add the cashews, water, miso, lemon juice, and salt to a high-speed blender. Blend until smooth, and add 2 to 3 more tablespoons of water, as needed, to help it blend. Set aside.
Drain and rinse the canned lentils, then add them to a large bowl. Stir in 1 cup of marinara sauce, and 3/4 of a teaspoon of salt. Set aside.
To assemble the lasagna, spread 1 cup of marinara sauce on the bottom of a 9 x 13-inch pan. Add a layer of lasagna noodles, without much overlap, then top them with half of the lentil mixture and half of the ricotta mixture. Spread it out evenly with the back of a spoon.
Drizzle 1/3 of the cheese sauce over the ricotta layer, then repeat the layers, starting with another layer of lasagna noodles, followed by the rest of the lentil mixture and ricotta. Drizzle another 1/3 of the cheese sauce over the top.
Add a final layer of lasagna noodles, and top them with 1 1/2 cups of marinara sauce, making sure the noodles are fully covered in sauce. Drizzle the remaining cheese sauce over the top, then cover the pan and bake at 400ºF for 45 minutes. Remove the cover for the last 5 minutes of baking, so the top will dry slightly.
Let the lasagna rest for 10 to 15 minutes, then slice and serve warm. Leftover lasagna will keep well in the fridge for up to 5 days. (I think it tastes even better the next day!)
Nutrition information is for 1 of 6 large slices. You can cut this into smaller pieces for a lower calorie dish, if needed. This information is automatically calculated, and will vary based on the brands you use.If you don't have miso on hand for the Cashew Parmesan sauce, replace it with a 1/2 teaspoon of salt, instead.