Preheat the oven to 180 ° C. First prepare the "crust". Rinse the quinoa with water. In a saucepan, boil the 2 cups water and add lemon juice, soy sauce, vegetable powder, salt and pepper. Add the quinoa and cook for about ten minutes until it absorbs all the water and doubles in size. Allow to cool completely and add the beaten egg, parmesan cheese and some pepper and stir.
Meanwhile, put a little olive oil in a pan and cook the onion .When softened, add the mushrooms and bake for a few minutes until the liquid evaporates. Add the spinach with salt and pepper and bake for another 2-3 minutes. Remove the pan from the fire and allow to cool.
In a round heat-resistant dish with parchment paper, add the quinoa mix and using your hands press the quinoa down and on the sides on the dish to form a base for the quiche. Bake the base in the oven for about 20 minutes. Remove it from the oven and allow to cool.
In the meantime, prepare the filling. In a pan, put the milk, eggs and Gruyere cheese. Add the mushrooms and spinach that have cooled and blended. Pour the mixture on the quinoa base, sprinkle the gorgonzola cheese on top and bake in the oven for about 40 minutes until the surface and sides are golden brown.
Allow the quiche to cool for a few minutes, cut into pieces and serve with salad.