Arrange 3 saucepans on the stove. In one, combine 4 cups water, 1 cup sugar, the white wine and the vanilla bean. In the next, combine 5 cups water, 1 cup sugar, the grenadine, lemon zest and lemon juice. In the last, combine 3 cups water, 1 cup sugar, the red wine, orange zest and orange juice. Bring to a simmer over medium-low heat, stirring occasionally. Meanwhile, peel the pears and cut them in half from top to bottom. Using a melon baller, scoop out the seed pocket. Using a small knife, cut a shallow V down the center of the pear's cut face to remove the stem, strings, and bud end.
Cut out 3 circles of wax paper the same size as the saucepans. Place 4 pear halves in each saucepan and rest a waxed paper circle on top. Bring to a gentle simmer and simmer without stirring until tender, about 15 minutes. When the pears can be pierced easily with a fork, they are done. Turn off the heat and let cool in the liquid. Serve at room temperature, or refrigerate in the liquid overnight to let the pears absorb even more color and flavor. Bring to room temperature before serving. To serve, arrange one pear half of each color in a spoke pattern on a white plate. Drizzle a spoonful of the grenadine poaching liquid over the pears and serve.
Courtesy Gale Gand, "Butter Sugar Flour Eggs" by Gale Gand, Rick Tramonto, Julia Moskin, Clarkson N. Potter Publishers, 1999