chicken, onion, and mozzarella sandwiches with roasted potatoes... 35 minutes

the goods:

1 tablespoon extra-virgin olive oil, plus more for brushing

1 and 1/2 pounds small new potatoes, halved if large

1 small red onion, cut into 1/2-inch rounds

4 chicken cutlets

4 slices fresh mozzarella

4 ciabatta rolls, split

lettuce, for serving

sliced tomato, for serving (optional)

mayonnaise, for serving

Preheat oven to 400 degrees. Brush a rimmed baking sheet with oil. Place potatoes at one end and onion at the other end; brush vegetables with oil and season with salt and pepper. Bake until potatoes are tender and onions are soft and browned, 30 minutes, flipping halfway through.
Meanwhile, in a large cast-iron or heavy skillet, heat oil over medium-high. Season chicken on both sides with salt and pepper. Cook chicken until browned and cooked through, 5 minutes, flipping once. Top each cutlet with 1 slice cheese, cover skillet, and cook until cheese is melted, 1 minute. Layer cutlets on bottom halves of rolls with onion and lettuce (and tomato if using). Spread mayonnaise on top halves of rolls. Sandwich and serve with roasted potatoes.