Dice fresh tomatoes and finely chop red onion. Combine them in a bowl with chopped basil, olive oil, salt, and pepper. Mix gently and pat dry to remove excess moisture.

Brush one side of each ciabatta slice with olive oil. Layer fresh mozzarella and bruschetta mixture on the unbrushed sides.

Stack the oiled slice on top of the filled one, ensuring the brushed side faces out. Press down gently.

Preheat a non-stick griddle or frying pan over medium heat. Grill the sandwiches for about 3-5 minutes on one side until golden before flipping.

Rub garlic on the grilled side of the sandwich after flipping. Grill until the other side is golden, about another 3-5 minutes.

Transfer cooked sandwiches to a serving plate. Drizzle with balsamic glaze and slice in half to enjoy.