Wash and dry all produce. Preheat the oven to 400 degrees. Remove the core and seeds from the bell pepper and cut into 4 panels. Cut the mozzarella into 8 slices. Finely chop the oregano leaves. Place the peppers and portobello caps on a baking sheet and drizzle with olive oil. Season with oregano, salt, and pepper. Roast for 15-20 minutes, until very soft.

Slice each ciabatta in half widthwise. Drizzle with olive oil and toast in the oven for about 5 minutes. Halve the garlic cloves, then rub each ciabatta with the cut side of the garlic.

Once they are ready, slice the peppers and portobello mushrooms into thin strips. Place the ciabattas onto the baking sheet and top each with alternating layers of mozzarella, mushrooms, and peppers. Place in the oven for 5-6 minutes, until melted.

Toss the salad: In a medium bowl, toss the spinach with 1 Tablespoon balsamic vinegar and a drizzle of olive oil. Season to taste with salt and pepper.

Serve the open-faced portobello sandwiches with the spinach salad and enjoy!