"Before I became a vegetarian, I used to love BLTs. Here is a great alternative to BLTs with all the flavor and none of the meat. While tempeh has a texture different from bacon, I like it better than any of the fake bacon products I've tried."
Heat oil in a skillet over high heat; cook tempeh bacon in the hot oil until lightly browned, 2 to 4 minutes per side.
Spread mayonnaise on 1 side of each bread slice. Layer 1 leaf lettuce, 1 tomato, and tempeh bacon on the mayonnaise side of 1 bread slice. Top tempeh with remaining tomato slice and lettuce leaf. Place the remaining slice of bread, mayonnaise-side down, on top.