Using a sharp knife, slice the tomato into 1/2-inch slices. Sprinkle with salt and pepper and let sit.
Slice the block of tofu into in half, running your knife through the block parallel to the cutting board. Using a 2-inch cookie cutter or small drinking glass, carefully cut out 4 circles from the tofu. (This is all a little tricky - silken tofu's very delicate and kind of a pain to work with, so don't feel like you have to cut circles if it's not working out for you - you can also just slice rectangles off the block. Circles make it look more like mozzarella, but that's pretty much the only advantage.) Sprinkle with salt and pepper to taste.
On plates or a serving platter, layer the slices of tomato and tofu so that they overlap slightly. Sprinkle with the sliced basil, drizzle with the olive oil and vinegar, and add maybe a little sea salt if you want some extra salty crunch on top.