I started a new job in Charlestown. We go for lunch in the neighborhood almost every day. So far, we've tried Charlestown's only Thai restaurant, the Warren Tavern, the Ironsides Grill, and a couple of yuppie sandwich shops.
The Ironsides grill has excellent food, and a nice patio. I recommend their chicken, blue cheese and walnut salad and the unsweetened iced tea.
The Warren Tavern's has pretty good food and aggressive air conditioning (a major attraction when our air conditioner wasn't working this summer). The Buffalo chicken burger is quite good. The WT makes its own potato chips. They're not spectacular, but they're a fun alternative to french fries.
The Thai place has a solid lunch buffet.
Does anyone have any other suggestions, preferably within walking distance of the Beacon Hill Monument.