Fry the mushrooms until brown and set aside.
In the same pan/sufuria, fry onions and garlic until fragrant. Add 1/2 the amount of the cooked mushrooms and fry them for 2 minutes.
Add the black pepper, cumin, coriander and paprika. Stir well and let it cook for 2 minutes.
Add the rice and toast it for 3 minutes. Add salt to taste.
Using the ratio of 1:2 ( rice : water ), add boiling water to the rice and the rest of the cooked mushrooms.
Let the rice cook on medium heat for 15 - 20 minutes.
Once cooked, add leeks and grated cheese.