Add 1 teaspoon fresh lemon juice, 1/4 teaspoon lemon zest, 1 teaspoon finely chopped parsley, 1 teaspoon finely chopped chives, and 1/4 teaspoon minced garlic. Stir to combine.

Season the spread with 1/8 teaspoon salt and a pinch (1/16 tsp) black pepper. Taste and adjust—add a touch more lemon or salt if desired. Set aside while preparing the sandwich.

Sandwich Assembly

Prep bread and toast

Lightly butter one side of each sourdough slice with 1 teaspoon softened butter (or brush with olive oil). Toast the bread in a skillet over medium heat or in a toaster until golden and crisp, about 2–3 minutes per side in a skillet, or 3–4 minutes total in a toaster. Remove and keep warm.

Prepare avocado

Scoop the flesh from 1/2 ripe avocado into a small bowl. Mash gently with a fork until slightly chunky. Season with 1/8 teaspoon kosher salt and 1/8 teaspoon freshly ground black pepper. If you prefer, leave avocado in slices rather than mashing.

Assemble layers

Spread half of the lemon-herb spread evenly over the cut side of both toasted sourdough slices (about 1 tablespoon per slice). On the bottom slice, place the butter lettuce leaves, then arrange 3 oz sliced roasted turkey in a single layer.

Top the turkey with mashed (or sliced) avocado, spreading it evenly. Layer 3 tomato slices, 4 cucumber slices, and 4 red onion rings. If using, add 1 slice of cheddar or pepper jack on top.

Season and finish

Sprinkle a light pinch of kosher salt (about 1/8 tsp) and a small grind of black pepper over the tomato and avocado layer. Place the top slice of bread, spread-side down, to close the sandwich.

Serve

Press lightly, cut the sandwich in half if desired, and serve immediately with an optional lemon wedge on the side for an extra bright squeeze.