Make the Dressing:
In a mixing bowl or jar, whisk together tahini (or mayonnaise), olive oil, lemon juice, Dijon mustard, Worcestershire sauce, grated garlic, salt, and pepper. Stir in the Parmesan. Add cold water gradually until the dressing reaches your desired consistency. Taste and adjust seasoning as needed.

Assemble the Sandwich:
Preheat your oven to 400°F. Place both halves of the ciabatta bread, cut side up, on a flat surface. Scoop out some of the inside from the top half of the bread to make room for the fillings. Spread the prepared dressing on the bottom half of the bread. Add a layer of basil pesto on top.

Layer the Fillings:
Top with sun-dried tomatoes and pepperoncini slices. Add the turkey, followed by the slices of Gouda (or Havarti) and provolone. Lightly season with salt and pepper.

Bake:
Place the open sandwich in the oven and bake for about 15 minutes, or until the cheese is fully melted.

Add Fresh Toppings:
Remove the sandwich from the oven. Layer the sliced avocado over the melted cheese and add the broccoli sprouts or microgreens. Drizzle with a bit more dressing if desired.

Finish and Serve:
Place the top half of the ciabatta on the sandwich and press down gently. Return to the oven for another 5 minutes to lightly toast the top. Remove, slice into six portions, and serve warm.