SLICE tomatoes ¼-inch thick and season with a pinch of salt and pepper.
COMBINE in a small bowl, mayonnaise, basil, lemon, remaining salt and pepper. Mix well.
PLACE all 8 slices of bread on a clean work surface and spread ½ tablespoon (1 1/2 teaspoons) mayonnaise on each slice. Lay tomato slices on half of the bread slices and place the tops on each sandwich. Cut in half and serve immediately.