Preheat oven to 400 degrees and line or grease 2 muffin tins(only if baking muffins immediately).
In a small mixing bowl combine the boiling water with 3/4 C bran and stir well. Stir in the cranberries and oil and set aside.
In a separate, larger bowl, stir together the flour, baking soda, baking powder and salt. Set aside.
In another bowl, beat the egg with the buttermilk(or milk mixed with lemon juice or vinegar) and orange juice. Add this mixture to the dry ingredients along with the remaining 1/2 C of bran and the bran-cranberry mixture. Mix well. At this point you can cover the mixture and refrigerate overnight and bake the muffins in the morning if desired.
Gently fold in the chopped apple and divide the batter between 24 muffin cups(for smaller muffins) or as little as 20 for larger muffins(increase bake time slightly for larger muffins)
Place in the oven and bake for 12-13 minutes, or until a toothpick comes out clean. Cool for 5 minutes in the muffin tin, then remove and place on a wire rack to cool completely or serve while still warm.