1 For each sandwich, toast two slices of whole grain bread. While the bread is toasting, slice your tomato and avocado.
2 Slather as much mayonnaise as you like on one side of each slice of toasted bread. Add a layer of sliced avocado and sprinkle a little kosher salt over it. Add a layer of lettuce and a layer of sliced tomatoes. Sprinkle a little salt over the tomatoes too.
3 Top with the second slice of toasted bread. Cut the sandwich in half if you want, to make it easier to eat.