Place apples in acidulated water and set aside.

Preheat oven to 350ºF. Line a baking sheet with parchment paper. 

Work oats, flour, room temperature solid coconut oil, sugars, salt, and cinnamon together in a bowl, with your hands, until the mixture holds together and resembles large crumbs. Fold in flax seeds and raisins. 

Remove apples from water and dry. Cut in half lengthwise. With a melon baller or small spoon, remove the core. Place ½ an apple on a cutting board with 2 wooden spoons on either side as cutting guides.

Cut slices, ¼ inch apart, while allowing the spoons to stop your knife going all the way through. This holds the apple together. Repeat with remaining apples. Stuff the slits with oatmeal mixture and crumble any extra on top of apples.

Brush apple halves with coconut oil, and bake at 350°F for 30 minutes, or until softened and lightly golden brown. Serve apples warm or at room temperature.