Light brown sugar
3 pounds good-quality lump charcoal
Cut the pineapple into wedges or spears. Press the cut sides into the brown sugar. Cut the peaches in half, remove the pits, and lightly oil the peach halves. Lightly brush oil onto the plums.
Set up the cooker for direct cooking: Open the top and bottom vents. Pile 2 pounds of the charcoal in the bottom. Load a charcoal chimney one-quarter full of charcoal and light it. When the coals in the chimney are glowing, dump them on top of the pile already in the cooker and close the lid. Adjust the vents as necessary to establish a steady temperature between 350to 375 degrees for direct grilling.
Open the cooker and spread the fruits evenly over the charcoal, cut side down, and cook for 3 to 4 minutes, or until they soften and are nicely marked. Pull the fruits off the cooker and arrange on a large serving tray.
Serve immediately or at room temperature.