Preheat the oven to 350 degrees F.
Place the bacon in a single layer on a rimmed baking sheet and bake for 10 minutes, turning it once, until crisp. Transfer to a plate lined with paper towels and when cool enough to handle, break into large pieces. Pour 1 tablespoon of the bacon grease into a small bowl.
On a separate rimmed baking sheet, toss the bread cubes with the oil and blue cheese, and bake for 20 minutes, tossing occasionally, until the cubes are crisp.
To the bowl with the bacon grease, whisk in the mayonnaise, lemon juice, tomato paste, and pepper.
To serve, place the lettuce wedges on 4 plates. Drizzle with the mayonnaise mixture and scatter the blue cheese croutons, tomato, and bacon over the top.