Ground Meat and Burdock Root over Rice

Name: Ground Meat and Burdock Root over Rice
Ingredients: 150 g ground pork (mixed beef and pork or just beef is OK); 1 large burdock root; 1 tablespoon ginger, grated (or about 3 inches if using a tube); 1 tablespoon garlic, grated (or about 3 inches if using a tube); 2 tablespoons sake; 2 tablespoons water; 2 tablespoons soy sauce; 2 tablespoons mirin; green onion, to taste; 1 teaspoon sesame oil; 1 -2 cup cooked rice (2 cups if serving over plain rice, 1 cup if serving over fried cabbage and rice); 1 1/2 cups cabbage, shredded (optional); shichimi chili powder, to taste