I had heard of this place through email, and when my office moved to Reston I drove past it out of curiosity. The location left me very unimpressed - it was a half-vacant strip mall with few cars in the parking lot. However, I had read very good reviews, & wanted a change from Reston Town Center, so I decided to give it a try. I'm glad I did!
The ambience is lovely - as soon as you get inside, you feel like you're elsewhere. White tablecloths & stemware are always pretty nice, but the arches and the mural covering the entire wall were unique and beautiful. It was surprising to see that the restaurant was busy and bustling. I was greeted right away, and our reservation was easily found.
I was there to catch up with a professional mentor over lunch. We both got the crab & avocado salad, which was creamy & flavorful. She mentioned that she'd ordered the same dish from another well-known restaurant in Tyson's Corner the previous week, but this one was much better. She also enjoyed the gazpacho, & I enjoyed the ice tea & coffee. Service was very good as well - attentive without being intrusive.
Apparently they can accommodate larger groups as well. There were plenty of tables with just two guests - but at one point, I heard applause break out from the other side of the restaurant near the bar, and noticed that there were tables lined up for a group of perhaps 15 or 20.
El Manantial is a "hidden gem" that was a nice break from the work day. Don't let the location fool you, & give it a try!