Wash, peel, and core a fresh pineapple. Place the peels and cores in a 1/2 gallon jar. (Use the delicious fresh pineapple for another recipe or enjoy it fresh!)
Peels from one pineapple
Pour sugar into jar and fill with water to within an inch of the top.
1/2 gallon water, 1/2 cup sugar or piloncillo
Cover jar loosely. You can use a cloth napkin attached with a rubberband or a jar lid that's not tightened down. (This allows any built up gasses to escape.)
Leave the jar out at room temperature for several days. Watch for the formation of bubbles. Sample the tepache about 24 hours after the bubbles formed. It may be delicious at that point, or you may decide to let it sit at room temperature for another 24-48 hours.
Pour the liquid through a fine sieve to remove particles.
Store in the refrigerator in a sealed jar for up to 2 days.
Notes
You can try adding a knob of fresh ginger (shredded) into the jar, or add whole cloves or a cinnamon stick to vary the flavor.
There are some variables in this recipe (as with most fermentation recipes). Experiment and try it more than once! Each batch is slightly different.