Wash rice and drain. Grind garlic, mint, coriander, green onions, cumin, cinnamon stick, and ginger together in a blender. Transfer to a small bowl and add yogurt; mix well.
Heat oil in a large skillet over medium heat. Add curry leaf and yogurt-spice mixture; saute until fragrant, 2 to 3 minutes. Add the washed rice and mixed vegetables. Saute until rice is well-coated with spices, about 2 minutes. Add boiling water, coconut milk, and salt. Reduce heat; cook until water is mostly absorbed, 5 to 10 minutes.
Mix ghee into the rice mixture in the skillet. Cover and cook until rice is soft and fluffy, sprinkling in more water if necessary, about 5 minutes more. Allow to sit for 5 minutes before serving. Stir in cashew nuts.