Finally, the Upper West Side has an upscale contemporary American restaurant to call its own. Ouest's menu is the brainchild of celebrity chef Tom Valenti, who rewards his loyal patrons with such signature dishes as petit filet with braised short ribs, sweet pea stew, and Parmesan pudding. There are also simple grilled meats, and lighter but such equally satisfying dishes as tuna "mignon" with white bean puree, black olive-lemon compote, and red pepper coulis. Request one of the circular red-leather booths near the open kitchen to see Valenti and his crew at work. Reservations essential. Subway: 1, 9 to 86th St.