Horchata in the US usually refers to rice-based Mexican horchata, but the original, Spanish version of this sweet, milky, grain or nut-based beverage is made with tiger nuts ("chufas" in Spanish, "xufes" in Valencian), water, and sugar. When I found out Valencia—specifically the town of Alboraya* just north of the metropolitan area—is the birthplace of horchata and the center of tiger nut production in Spain, trying fresh horchata became the number one thing I wanted to do in Valencia. I ended up drinking it five times from three different places.
* You'll find many horchaterias in Alboraya on the appropriately-named main street, Avenida de la Horchata/Avinguda de l'Orxata. Alboraya is also home to a horchata and tiger nut museum, Museo de la Horchata y la Chufa.
Most of the horchata I tried was from Món Orxata ("World Horchata" in Valencian), an Alboraya-based company started in 2003 that makes fresh horchata every morning from organically and locally grown tiger nuts and sells it from carts around the city, bringing back the hochata-cart tradition from the early 1900s. They also sell it at their two Orxata Coffee Shops and ship to other parts of Spain through their online store.
Món Orxata cart locations vary by season—there are more in the summer than winter—but the ones I came across were right by the Colon metro stop and at the Ciudad de las Artes y las Ciencias (City of Arts and Sciences), two areas you're likely to visit if you take a trip to Valencia.
I took a tour of the Món Orxata factory one morning to learn more about horchata. Check out how they make horchata in this slideshow »
How to Drink Món Orxata at Home
Like Mexican horchata, tiger nut-based Spanish horchata is also milky, nutty, and sweet, but with the flavor of...well, tiger nuts. The flavor is similar to soy milk or almond milk. I'd say there isn't much to dislike about something that's milky, nutty, and sweet, but Bizarre Foods host Andrew Zimmern found Spanish horchata disgusting, describing it as soy milk (a valid description) seasoned with stomach medicine (whoa, there). So maybe it's not for everyone. But I'd suggest you ignore him.
Unfortunately, since fresh horchata only keeps for 72 hours, it doesn't travel well outside of Spain. To drink the fresh stuff at home, you can try making it yourself from scratch by soaking and blending your own tiger nuts. Món Orxata sells tiger nuts in small packs that each make one liter of horchata. You can also buy tiger nuts at Mercado Central, but otherwise, whole dried tiger nuts aren't commonly found in stores in Valencia since it's easy to buy already-made horchata. You may also find tiger nuts from online retailers, like tienda.com.
An easier solution is to use horchata concentrate. Món Orxata's preservative-free concentrate lasts up to three years unopened, but once opened only lasts five days. You can also find horchata concentrate and ready-to-drink bottles in supermarkets, but they may be made with cheaper tiger nuts from Africa or contain preservatives. (Note: Not having tasted horchata made of Spanish tiger nuts against horchata made of African tiger nuts, I can't claim to know what the differences are.) Món Orxata doesn't export a bottled version of their horchata. Chufi is a brand of bottled horchata made from Valencian tiger nuts that you can find on Amazon.