That would be the relatively new Aroma in Olney, which heretofore had only one arguably outstanding restaurant (Mannequin Pis). The food is mostly Peruvian. I think Aroma is better than the Canelas in Rockville and Gaithersburg, or the various Spanish restaurants for that matter. Great ceviches, tapas, drinks and entrees. Even the superb desserts are freshly made by the chef in-house.
The food is fresh, well-seasoned and properly cooked. I have had the Lomo Saltado, Arroz con Marisico and Peruvian Chicken. All were the best versions I have ever had in the DC area.
Even better, on Mondays you can get any of 10 entrees, ordinarily priced between $17 and $20, for $10. I think that "Entertainment Book" you can buy has a 2-for-1 coupon as well. Lunch is cheaper.
It also has an extensive list of list of inexpensive Latin American wines ($20-$35). There is also a half-price wine night.
The place is relatively small, with a small bar and about 20 tables, but it's very clean and the decor is sleek and modern. (They will turn down the piped-in Latino music if you ask,)