My sister introduced me to
Num Pang a delicious Cambodian sandwich shop. Besides having one of THE BEST shrimp sandwiches I've ever eaten they also have awesome watermelon juice, which my sister (she is in the know about a lot of things) told me how to make. Turns out you need just 1 ingredient: watermelon. You don't need a fancy juicer, just a blender. I'm pretty sure you could do small batches in a food processor too if you didn't have a blender. I used my immersion blender.
