Place the prunes in a small bowl and add enough very hot tap water to just cover them. When soft (about 1 hour), pour off any excess water and mash to a coarse paste with a fork. (If skins don’t break up readily, chop prunes with knife or food processor.) Stir in the olive oil, lime juice and chopped garlic. Taste and season with salt (usually about 1/2 teaspoon).
Cut the baguette on a diagonal into 1/4-inch-thick slices. Toast in batches on both sides, under a broiler or using a toaster. Cut the slices of cheese to fit the baguette slices. Spread each baguette slice with a little of the savory prune salsa, top with a slice of cheese, drizzle with a little olive oil, then sprinkle with the fresh herbs and black pepper. Serve right away.