Prepare the bread: If using take-and-bake ciabatta, prepare it according to the package directions. Otherwise, gently toast the loaf in a toaster oven, if it fits. Allow the bread to cool slightly before assembling the sandwich.
Sandwich spread: Add the mayo and pesto to a small bowl. Whisk until smooth and evenly combined.
Dress the arugula: Add all the dressing ingredients to a Mason jar. Secure the lid and shake vigorously until well combined. Place the arugula in a large bowl and drizzle in just enough dressing to very lightly coat it. Toss gently with tongs. You may have a little dressing left over. (Dress the arugula immediately before assembling the sandwich, not in advance.)
Slice the bread: Place the ciabatta loaf flat on a cutting board. Hold a serrated knife parallel to the cutting board and carefully slice horizontally through the center of the loaf to create a top and bottom piece.
Add the spreads and cheese: Generously spread the pesto mayo over both cut sides of the bread, using as much as desired. If you’d like a saucier sandwich, mix up a little extra. Arrange 4 slices of provolone over the bottom half of the bread and the remaining 4 slices over the top half.
Layer the sandwich: Arrange 5 slices of ham and all 15 slices of salami over the bottom half of the bread. Add a thin layer of pickled red onions, using as much as you like. Pile the dressed arugula evenly over the meat. Drizzle with a little of the remaining dressing, if desired, then arrange the remaining 5 slices of ham over the arugula to help hold it in place.
Finish and serve: Carefully place the top half of the bread over the fillings and gently press down to secure the sandwich. Use a large, very sharp serrated knife to cut the loaf into 6 sandwiches. Serve immediately and enjoy!
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Notes
Note 1: Take-and-bake ciabatta is my favorite option because it’s warm, fresh, and lightly crisp. If your loaf is larger or smaller than 14 ounces, adjust the toppings accordingly.Note 2: A good pesto makes this sandwich! Use a fresh pesto you already love from the refrigerated section. In my opinion, nothing beats homemade pesto or Rana’s!Note 3: Not an onion fan? Feel free to skip them! Here’s how to make the quick-pickled red onions.Make Ahead and Storage: Assemble without the pesto mayo, pickled onions, or dressed arugula. Wrap tightly and refrigerate for up to 1 day. Add the remaining ingredients just before serving.