Step 1Heat 1 tablespoon butter in 3-quart non-aluminum pot over medium-high heat. Add onion. Cook until softened, 5 to 7 minutes. Add cabbage, apple, 1 1/4 cups water, jelly, vinegar, sugar, salt and pepper to taste. Bring to boil. Stir until well mixed, then reduce heat and simmer, covered, until very tender with a slight crunch, about 40 minutes. If mixture is too dry, add more water as needed. Stir in remaining butter. Taste and adjust seasoning, vinegar and sugar. (Can be made a day ahead and refrigerated. Let come to room temperature before reheating. Gently reheat on stove top or in microwave until hot, adding more water if needed. Adjust seasonings.) Serve hot.