Recently refurbished Sanyuanli Market is a haven for professional and amateur cooks alike in Beijing. But this market—with long rows of vendors selling fruits, vegetables, grains, meat, tofu, and pretty much anything else that fits a pot or pan—is also a place I recommend to visitors.
The market is relatively clean. The produce is top-notch. And vendors are used to foreigners and usually willing to follow a "try before you buy" policy. That makes it ideal for first experiences. I've seen visiting friends first try a mangosteen or sniff a particular spice, marvel at the many varieties of tofu, and become transfixed by sea creatures flopping about. In even an hour, you can squeeze a lot of experiences—and some fruits—out of this place.