Start by gathering all your ingredients. Slice the tomatoes into ¼-inch rounds. This will reveal their juicy cores. Drain the mozzarella and chop the marinated roasted red peppers. That sweet-smoky component is crucial for depth.

In a food processor or blender, add the garlic clove, basil leaves, mayonnaise, and lemon juice. Pulse until you have a vibrant green spread. Add salt and pepper to taste, making adjustments as needed. The goal is a creamy consistency with an aromatic kick.

Split the crusty baguette lengthwise. This might require some muscle; however, the texture should be hearty. Aim for a clean cut to make assembly easier.

Start by spreading a generous layer of the creamy basil spread on both halves of the baguette. Then, layer the arugula leaves, followed by the tomato slices.

Next, place the mozzarella slices atop the tomatoes. Ensure they overlap slightly to cover every inch.

Now, add the marinated roasted red pepper strips. You want to enjoy that flavor burst with each bite.

Drizzle the olive oil and balsamic vinegar over the layered ingredients. Finish off with a sprinkle of sea salt.

Close the sandwich. If you want to press it down gently, do so to help the ingredients meld together. Finally, slice into portions, either halves or quarters.