Thanks to StephenB for recommending H-20, the spicy fish 'soup'at Joe's Noodle House in Rockville as one of the best things to eat in the area.
A while back, Mike had the audacity to ask what were people's favorite dishes (a loaded question), but I'm glad that StephenB took a swing at it. Joe's is a real Chowhound find, though probably not a secret in Montgomery County. I live in Arlington, so I never would have found the place on my own.
It's listed under specialties, and is not called a soup on the menu. The very kind woman behind the counter offered to make it milder for me, but I declined. At first bite, I though I'd regret that decision, but after a while, my mouth got used to the heat and I tasted a very rich, tangy sauce (actually a huge bowlful of gravy!) It was super delicious, and maybe still I would opt for less heat the next time around, just to see what difference that might make. No doubt, this place is a real treat.