Dissolve the concentrated cube in 750 ml of water and bring to the boil. Reduce the heat to low and leave until the moment of use.
Finely chop the onion and garlic, and the mushrooms and peppers into 1 cm slices.
Heat a little olive oil in a pan and add the onion, which is cooked for 5 minutes, until soft. Add the garlic and Ras-el-hanout. Cook for 1 minute, then add the rice. Mix well, then gradually add the previously obtained soup, waiting for almost all the liquid to be absorbed before adding the soup. Cook like this, over medium heat until all the soup has been used, stirring frequently. The rice should keep its shape, but not too soft. You can also add water if needed.
Meanwhile, heat a little oil in another pan over high heat. Add the peppers and cook for 5 minutes until golden and soft. Transfer to a plate. In the same pan, add a little olive oil and mushrooms. Cook for 5 minutes until soft. Add salt and pepper and the already cooked pepper. Mix well. Remove from the pan and sprinkle with za'atar.
When the risotto is ready, add butter and half the amount of Feta cheese (in small pieces) and salt and pepper if needed.
Serve the risotto with the peppers and mushrooms on top. Sprinkle with the remaining Feta cheese.