Core cabbage and plunge it into a large pot of boiling salted water. Cover and boil for 5 minutes, drain in colander, and rinse under cold water. Remove individual leaves using your hands, or if too hot, use tongs. Set aside on a pan sheet lined with paper towels.
To make the filling: In a saucepan, cook rice and split peas in 3 cups water and ½ teaspoon salt o