Mince the onion and chop the chestnuts. Core and peel the pears, then cut them into ½-inch dice.
Melt the butter in a large skillet over medium heat until golden brown. Add the onion and sauté for a minute or so just to get them going. Add the red wine and cover the skillet. Simmer over low heat until the onion is tender and soft, about 5 minutes. Add the chestnut