Cut bread in half lengthwise and toast or grill to your preference.
Spread rosemary mayonnaise on both sides of the toasted bread.
Arrange the sliced steak on the bottom half of the bread, covering it entirely.
Evenly spread the Italian tapenade over the steak.
Distribute roasted red pepper strips and fresh mozzarella slices evenly over the steak.
Top with baby spinach and cover with the top half of the ciabatta.
Cut into 4 sandwiches and serve.