Intensely flavorful ginger imparts piquancy to poached pears.
Bring all ingredients except pears to a simmer over medium-high heat in a large saucepan. Reduce heat to medium-low; cook 5 minutes.
Meanwhile, peel pears and cut in half lengthwise. Use a small spoon or melon baller to scoop out core and seeds from each half, leaving stems intact. Trim fibrous strip from center with a paring knife. Gently lower pears into pot. If not completely covered by liquid, lay a piece of parchment paper directly on pears.
Cook until a paring knife slides easily into pears, meeting slight resistance, 15 to 20 minutes. Remove from heat; let cool in liquid 30 minutes. Use a slotted spoon to transfer pears to a large bowl; cover with parchment paper. Cook liquid over medium heat until syrupy, about 15 minutes; discard vanilla pod and ginger. Let cool. Serve two pear halves in each bowl; spoon syrup over pears.
These pears may be refrigerated in their cooking liquid overnight.