To make the sauce: Combine the vinegar and honey in a small saucepan, bring to a simmer, and simmer until reduced to 1/2 cup. Let cool. Taste the sauce with a little of the ice cream and adjust the balance of sweetness with more honey if necessary—though I advise you to keep it fairly tart in contrast with the ice cream. Put a scoop of ice cream in each serving dish, with or without fruit, and drizzle with sauce—it’s powerful, so use just a little. (Any leftover sauce can be stored in a covered container in the refrigerator for at least several weeks.) Serve at once. Pass the olive oil separately, if using, and add a couple of crostini, if desired.
* Olive Oil Crostini
Toast 8 slices from a regular (not sourdough) baguette in a toaster oven or on a baking sheet in a preheated 350°F oven, turning the slices once, until lightly golden at the edges and perfectly crisp and crunchy. Brush or drizzle the tops liberally with extra virgin olive oil.