The B.L.T. has met its match. Sweet cabbage lightly sautéed with a hint of lemon, anchovy, and onion complements crisp, salty bacon and a smear of mayonnaise on lightly toasted bread.
Cook bacon in a large skillet over medium‐high heat, flipping once, until crisp and golden brown, about 8 minutes. Transfer to a paper‐towel‐lined plate.
Wipe skillet clean; return to medium‐high heat. Swirl in butter until melted. Add anchovies and onion; season with salt and pepper and cook, stirring occasionally, until just beginning to brown, about 6 minutes. Add cabbage and 1/4 cup water; season with salt and pepper. Cook until cabbage is wilted slightly but still crisp‐tender, about 5 minutes. Stir in lemon juice; season with salt and pepper. Spread mayonnaise onto one side of each bread slice; sandwich cabbage mixture and bacon. Serve immediately.