How to Make It
Preheat the oven to 400°. Line a large rimmed baking sheet with parchment paper or foil. For each lattice, weave 6 strips of bacon, 3 in each direction, on the prepared baking sheet.
Set an ovenproof rack upside down on the bacon to keep it flat. Bake for 15 to 20 minutes, until browned and crisp. Remove the rack, then transfer the bacon lattices to paper towels to drain.
Meanwhile, in a small bowl, whisk the mayonnaise with the tarragon and lemon juice. Season with salt and pepper.
Spread the tarragon mayonnaise on each slice of toast. Arrange the sliced avocado, cucumbers and tomato on 4 slices of the toast and sprinkle with salt and pepper. Top with the bacon lattices, Bibb leaves and sprouts. Close the sandwiches and serve.