1. Bring a large pot of salted water to a boil for the rice. Trim the ends of the zucchini and cut it into small cubes. Slice the onion. Add the rice to the pot and cook it covered for 12 to 14 minutes. Drain and set aside without the lid.
2. Heat olive oil in a skillet over high heat. Sauté the zucchini cubes with the onion for 1 to 2 minutes, then reduce the heat and continue cooking for 6 to 8 minutes or until they are tender and slightly golden. Season with salt and pepper. Meanwhile, squeeze or mince the garlic. Cut the lemon into quarters and chop the parsley.
3. Heat a skillet over high heat and toast the cashews until they start to brown. Remove the skillet from the heat. Set the cashews aside. Return the skillet to medium heat and add the butter. Add the garlic, cumin, and chili flakes. Cook for 1 minute, stirring. Add the shrimp and cook for 2 to 3 minutes. Add half of the parsley, squeeze a few drops of lemon according to your taste (watch out for the seeds). Mix, season with salt and pepper.
4. Serve the rice in shallow plates and pour the zucchini mixture over it. Place the shrimp on top of the zucchini and drizzle with the butter sauce. Add the remaining parsley and cashews. Serve with lemon quarters on the side and adjust the seasoning with salt and pepper.