In salted boiling water, lower a bag of rice. Simmer for 15 minutes. At the end of cooking, take out the bag and let the water drain.
Fry the cashew nuts in a dry pan, stirring, until they have a characteristic smell and golden color, about 3 minutes.
Make the pesto.
Grind the nuts, arugula, garlic clove, and olive oil in a blender (add the amount of olive oil based on your preferences for taste and consistency).
Cut the mushrooms into slices. Quickly fry in olive oil in a preheated frying pan.