They were warm, having just been roasted, and they were lightly sweet. They have a nutty taste, but it's much gentler than that of a peanut or an almond.
Castañas asadas actually seem quite easy to make. As a street food, they're prepared on coal-fired grills set up in little stands across Calle Mayor, the main pedestrian--or walking--street in Alcalá. No cars can go down that street, so it's the perfect spot for them. One person is in charge of each stand, and they put on the chestnuts in a continuous stream. Don't forget to pierce the chestnuts' shells so they don't explode!
Once the chestnuts have roasted (you can tell, because the shells get all wrinkly), the person in charge of the booth takes them off the coals and puts them on a different metal plate, covered in a towel to keep them warm. And that's it! Now you're ready to buy some castañas asadas, 8 for €1.50 or 14 for €2.50!
Chestnuts are a cultural staple here in Spain. They're grown in abundance (a lot of them) in Northern Spain, and in the fall lots of communities host some version of a castañada (again, chestnut) festival. So not only are they delicious, they're local and relatively sustainable.
Castañas are also culturally significant, and they form part of some holiday traditions. For example, in Canarias, Spain, where I was two years ago, castañas are part of the holiday of Finao, which is similar to Day of the Dead. It happens October 31st through November 2nd; perfect chestnut season! On Finao, you remember you loved ones.
