An unmarked door at the end of a tiny parking lot in Northeast leads to a hidden restaurant space that doubles as chef/owner Peter Cho’s home, charming front yard and flaming retro stovepipe hearth included. Han Oak is as seat-of-pants as a restaurant gets, sketched only with skill and imagination, defiantly open to chaos. Cho’s dumplings are crinkled bundles of bombastic pleasure that speak directly to the reptilian brain. Hand-torn noodles in broth taste like the best part of wontons, all flap and chew. Farther down the menu, Korean fried chicken wings, titanic in crunch, could do hand-to-hand combat with medical marijuana. One week, Han Oak’s doing Korean barbecue; a few months ago, it was farm-fresh K-brunch. It all works out, even when it doesn’t.