Heat the cooking oil in a pot over medium heat. Add the chopped onions and fry until slightly golden. Increase heat to medium-high; add the ground beef and brown until no longer pink, stirring occasionally. Reduce heat to medium and add the nutmeg and turmeric powder.Stir well.
Add the crushed tomatoes and cook for 5-8 minutes, stirring often. Then add cooked rice, lentils, coriander, green onions, water, salt and pepper to taste. Cover the pot and bring to a boil, then reduce heat to medium-low and simmer until desired thickness, stirring occasionally. Add more water during cooking if necessary. Add lemon juice before serving.