If you know you'll be making these a few days ahead of time, I would toss the ginger into a bottle with 6 cups pineapple juice and let it infuse that way. Then add in the turmeric and shake. If you're doing it quickly, heat the pineapple juice, ginger and turmeric in a large pan and bring to a boil, whisking. Simmer for about 20 minutes, then let it cool back to room temp.
To make the cocktail, pour 2/3 cups juice into each 8oz glass jar. Then add in 1 1/4 oz unfiltered sake. Close the lid and shake. Then store in the refrigerator until cold before you serve.
Watermelon Lime Soju Cocktail
Cut the watermelon in half and scoop out the inside into a blender. Blend on high until it's liquid.
Strain through a mess strainer into a bowl with a spout. Then add in fresh lime juice from 2 1/2 limes.
Pour 2/3 cup juice into each 8oz glass jar.
Add in 1 1/4 oz (or more if you want!) Soju and shake. Store in the fridge until cold and then serve!
Notes
Servings, time and nutritional value based on Pineapple Ginger Sake Cocktail