Wash the peaches well in cold water, then cut them into wedges, discarding the pits, and place the wedges in a mixing bowl. (You can also peel them if you like, though I don't—see Notes below.) Sprinkle the peach wedges with the sugar and the juice of half a lemon. Mix gently with a rubber spatula to avoid bruising—ripe peaches are quite delicate—and allow the peaches to rest for about 15 minutes or so, or until the sugar has dissolved and the fruit has softened a bit.

Place the macerated peach wedges into individual serving bowls or glasses. Add enough red wine to each bowl or glass just to barely cover the peaches and allow them to macerate for a further 30 minutes or more. The longer they macerate in the wine, the more potent the wine taste will be—too long a maceration and the taste of the wine will come to dominate. I find that 30-60 minutes or so provides the right balance between wine and peach, but this is a matter of taste.