If you soak the spelt the night before it will ease cooking, but it is not essential.
Turmeric is fat-soluble, and thus it is important to pour it at the beginning, with the oil in the sautée. Ground black pepper enhances the turmeric's beneficial effects about 20 times.
The dish admits any other vegetable combination (peas, beans...) and other mushrooms (boletus edulis, shiitake, maitake...) according to your creativity, exactly the same as you would do with rice.