To dry the tomatoes, oil a large baking sheet. Halve the tomatoes lengthwise and cut in quarters. If they are very large, make the first cut off center, then cut the larger piece in two, having 6 cuts to 1 tomato. Trim away the cores. Place the pieces, cut side up, on a prepared baking sheet.
Sprinkle the sugar evenly over the tomatoes, and then season with salt and pepper. Drizzle the olive oil on top of all. Place in a 150° oven and leave for 8 hours or up to overnight. The tomatoes will be semi dried. If your are short of time, set the oven at 225° and reduce time to 3-4 hours. Check occasionally to make sure that the tomatoes are not baking but just drying.