Outside, only a few crimson leaves cling to the gnarled branches of the Japanese maple trees. Inside the Portland Japanese Garden’s modern tea room, glass walls show the forest giving way to winter. The setting may feel like something out of the Japanese countryside, but this oasis is some 5,000 miles away, nestled in a lush hillside in northwestern Oregon. In the 1960s, the city of Portland converted an old zoo into a 12-acre garden as part of an effort to promote peace and cultural exchange between the U.S. and…