Toast the bread: Lightly toast all 8 slices so they’re sturdy. This helps prevent sogginess and adds crunch.
Make a quick spread: In a small bowl, stir together mayonnaise, Dijon, lemon juice, red wine vinegar (if using), olive oil, a pinch of salt, and pepper.
Taste and adjust with more lemon or salt.
Prep the fillings: Slice the eggs and tomatoes, shred the lettuce, crumble the blue cheese, and slice the avocado. Season the tomato slices with a pinch of salt and pepper.
Season the chicken: Toss the chopped chicken with a spoonful of the spread and a sprinkle of salt and pepper. This keeps it juicy and flavorful.
Assemble the base: Spread a thin layer of the dressing on one side of each toast slice.
On four slices, add a generous layer of shredded lettuce.
Layer the stars: Add chicken, then tomatoes, then bacon. Top with egg slices, avocado, and a sprinkle of blue cheese. Add a few red onion slices if you like a bit of bite.
Finish with herbs: Sprinkle chopped chives or parsley over the fillings for freshness.
Cap and press: Place the remaining toast slices on top (spread side down).
Gently press to set the layers.
Slice and serve: Use a sharp knife to cut the sandwiches in half. Serve immediately with extra dressing on the side if you like.