I have a pineapple, so I googled 'fermented pineapple drink'. Now, this is what I've found and I think it looks very interesting and summery.
Fermented Pineapple Drink (Guarapiña o Mavi de Piña)
The recipe actually says to soak the oats for 10 minutes in buttermilk, so I figured, why not longer? And why not throw in some oat flour with it? Of course it says to use all purpose flour, 3 cups to be exact. So I used half that amount of oat flour, and for the other half of the flour I used half as much coconut flour (so that would be 1 cup) which I mixed with all the dry ingredients for the base. I followed the rest of the recipe except adding an extra egg to offset the coconut flour a bit, the oat flour also offsets the dryness of coconut flour because it's so moist.
Here's the recipe which will make 3 dozen, half it if that's too many muffins for your house!
3 cups rolled oats
1 cup oat flour
3 cups buttermilk (or soured milk, or equal parts liquid whey and water)
Mix this together in large bowl, cover, and soak for 12-24 hours.
When you're ready to bake the muffins preheat the oven to 375 and stir the following together in large bowl:
1 cup coconut flour
1 1/4 cup rapadura
3 tsp ground cinnamon
3 tsp baking powder
1 1/2 tsp baking soda
1 1/2 tsp real salt
Then add 2/3 melted butter and 5 fork beaten eggs to the soaked oat mixture. Add to dry ingredients and stir just until moistened. Fill buttered or papered muffin cups about 3/4 full and bake for 20 minutes.
mix 2 tbs rapadura and 1 tbs cinnamon together and sprinkle the tops of the muffins
decrease butter to 1/2 cup and add 3 cups grated peeled cooking apples to the egg mixture