Washington’s best pizza? Right now, it’s in Falls Church. That’s where Edan MacQuaid, a former talent at 2 Amys and Pizzeria Paradiso, is stoking the wood-burning oven at the new Pizzeria Orso, a big, friendly barn of a place done up in yellow walls, soft green booths and red sound-soaking panels, with images of bears here and there. (”Orso” is Italian for “bear.”) MacQuaid’s Neapolitan crusts are thin, pliant, a tad sour, beautifully charred -- and served unsliced, so the dough can continue to cook after it leaves the fire. His margherita upholds tradition with tangy crushed tomatoes, fresh basil and near-liquid pinches of genuine buffalo mozzarella, but the daily specials bear investigating, too: a round decked out with a lattice of grana cheese, briny capers, red pepper flakes and juicy mussels in their shells deserves a permanent place on the menu. Pizza isn’t the only thing the kitchen does well. Tender lamb meatballs in a zesty tomato sauce, and fritters that crack open to a fluff of potato and cheese, tempt you to make a meal of appetizers, while the crisp cannoli stuffed with sweetened ricotta and pistachios practically demand that you stay for dessert.