This condiment can be made a day or two aheadof time; warm before serving.
Peel and cut onions in half lengthwise and slice into 1/4-inch-thick semicircles. Place in a large skillet with butter, 1 1/4 cups water, honey, vinegar, and pepper to taste. Bring to a boil; cook over medium-low heat until most of the liquid has evaporated and onions are very soft, about 40 minutes. Continue to cook until onions are a deep golden brown, about 15 minutes more. Addwater as needed to keep onions from scorching. Stir in currants and serve.