1. Wash your pineapple thoroughly, scrubbing the peel to remove any dirt or impurities. You can use a vegetable brush. Cut off the crown and base, then carefully peel the pineapple, keeping the peels as intact as possible.

2. Dice the pineapple flesh for another use. You only need the peels for this recipe, though a few chunks of fruit can be added for extra flavor.

3. In a large, clean glass jar (about 1-gallon capacity), combine the pineapple peels, brown sugar, and cinnamon stick.

4. Pour in the filtered water, stirring well to dissolve the brown sugar. Ensure the peels are mostly submerged.

5. Cover the jar opening with a clean cheesecloth or a breathable kitchen towel, securing it with a rubber band. This allows air in while keeping pests out.

6. Place the jar in a warm spot (ideally 70-80°F / 21-27°C) away from direct sunlight. Let it ferment for 24 to 72 hours. You'll start to see small bubbles forming on the surface, indicating fermentation is active. Taste daily after 24 hours until it reaches your desired level of fizziness and sweetness. The longer it ferments, the less sweet and more tangy/alcoholic it becomes.

7. Once fermented to your liking, strain the liquid through a fine-mesh sieve into clean bottles or another jar, discarding the solids. You can optionally strain it again through a cheesecloth for an even clearer liquid.

8. Seal the bottles tightly and refrigerate. Tepache will continue to lightly ferment in the refrigerator, but at a much slower pace. Enjoy chilled within 1 week.