A luscious beefsteak tomato, such as the Big Rainbow variety, makes for a delicious open-faced sandwich.
Brush rustic bread slices with extra-virgin olive oil. Toast in a heavy skillet (preferably cast-iron) over medium-high heat until golden, about 30 seconds per side; transfer to a platter.
Halve ripe beefsteak tomatoes; brush cut sides with oil. Sear facedown in skillet, without moving, until charred, 4 to 5 minutes. Use a metal spatula to loosen tomatoes from pan. Transfer to bread; lightly mash. Season with coarse salt and freshly ground pepper. Sprinkle with fresh oregano.