Prepare the Toasts: Gently warm the olive oil in a large skillet or flat-top griddle over medium heat. Place the sourdough slices in the pan (you may need to do this in batches depending on pan size). Toast each side for approximately 2-4 minutes, aiming for a consistent golden-brown color and a surface that's crisp to the touch. Transfer the finished toasts to a wire rack or platter.

Make the Avocado Spread: While the bread toasts, halve the avocados lengthwise, remove the pits, and scoop the flesh into a medium-sized bowl. Add the fresh lemon juice, salt, black pepper, and optional red pepper flakes. Using a fork, mash the ingredients together until combined but still slightly chunky for texture. Avoid over-mashing into a completely smooth paste.

Assemble the Toasts: Spread a generous, even layer of the prepared avocado mixture onto one side of each toasted sourdough slice, covering it from edge to edge.

Add Toppings: Artfully arrange the halved grape tomatoes and fresh mozzarella pearls over the avocado layer on each toast. Ensure a balanced distribution for visual appeal and flavor in every bite.

Finish and Serve: Drizzle the balsamic glaze over the toppings on each toast; a zigzag pattern often looks appealing. Garnish generously with fresh basil leaves. Serve immediately for the best texture and temperature contrast.