Have to rave about a warm salad we had last night at prose on Mass Ave in Arlington (near the center). Slightly stewed rhubarb and toasted pecans mixed with bits of Berkshire Blue cheese atop the freshest, most tender baby leaves of red swiss chard - the colors were also quite lovely. I've never had such a combination and it was soooo satisfying: tart, rich, and nutty all perfectly balanced. My entree was also great (perfectly cooked black sea bass with wild mushrooms atop perfectly cooked pea greens), but that salad ruled the day!
One note if you go to prose: it's a one-woman kitchen with one waitress. You should expect a leisurely dining experience but the food is worth it and the prices are quite reasonable.