Sigh of relief: Petworth’s hot-test dining room has finally started taking reservations, so you no longer have to wait hours to land one of its 24 seats and a taste of Kevin Tien’s often brilliant pseudo-Japanese menu. What brings that subtle sweetness to the bigeye-tuna tartare? The tiny cubes of beet hiding in the mix. Its other accessories—fermented-chili aïoli, puffed rice—make the bowl taste like the spicy tuna roll of our dreams. This is a place to order widely—rich shrimp toast, charred octopus with black-bean mole, Japanese-style fried chicken—and share everything. Don’t forget the fanciful drinks conjured up by co-owner Carlie Steiner. Expensive.