Prepare the eggplant: 

1. Place a clean kitchen towel (or several layers of paper towels) inside a rimmed baking sheet. 
2. Lay the eggplant slices on the kitchen towel and sprinkle ¾ teaspoon salt over one side of the eggplant slices. Flip the eggplant slices around and sprinkle another ¾ teaspoon salt over the opposite side. 
3. Let the salted eggplant sit at room temperature for 30-40 minutes, until beads of moisture form on the surface. 

Roast the eggplant:

1. Preheat the oven to 400 degrees. 
2. Use a clean kitchen towel or paper towels to pat the eggplant slices dry and remove some of the salt. 
3. Line another rimmed baking sheet with aluminum foil and lay the eggplant slices over the foil. 
4. Pour the olive oil into a medium bowl and add the grated garlic, dried oregano and red chili flakes to the oil. Use a pastry brush to brush both sides of the eggplant slices with the herbed olive oil. 
5. Note: if you don’t have a pastry brush, you can spoon the olive oil onto the eggplant slices. 
6. Cook the eggplant in the oven until the centers are completely soft and the eggplant is golden brown, 45-55 minutes. Remove the baking sheet from the oven halfway through baking and flip the eggplant slices over for even roasting. 
7. Note: Eggplants soak up a lot of oil. If they look dry when you’re flipping them over, drizzle with a bit more olive oil over the eggplant. 
8. Remove the cooked eggplant from the oven but keep the oven turned on to 400 degrees. 

Preparing the arugula:

1. Place the arugula in a large bowl and squeeze the fresh lemon juice over the arugula. Toss to completely dress the greens with lemon juice. 

Assembling the sandwiches: 

1. Place the bottom half of the ciabatta rolls on a foil lined baking sheet. You can reuse the foil-lined baking sheet you used to roast the eggplant.
2. Top the ciabatta bottoms with 3-4 slices of roasted eggplant and a few slices of roasted bell peppers.
3. Top the sandwiches with a slice of provolone cheese each.  
4. Place the ciabatta tops, cut side down, on the baking sheet next to each sandwich. 
5. Place the baking sheet in the oven and heat the sandwiches until the cheese has melted and the bread is warmed through, 3-4 minutes. 
6. Remove the sandwiches from the oven and slather some whole grain mustard over the cut side of the ciabatta tops. 
7. Top the sandwiches each with a pile of the dressed arugula.
8. Sandwich the mustard-glazed ciabatta tops on top of the arugula and enjoy the sandwiches warm or at room temperature.