Chop the tomatoes, fresh basil, and mozzarella and add to a bowl. Add salt and pepper and mix.
Brush the bread slices with olive oil (using a pastry brush or simply drizzling the olive oil on the bread). Then grill/toast the bread in a skillet, cast iron pan, or grill pan for about 2 minutes on each side over medium-high heat until lightly browned and toasted. Note: You can also choose to skip the olive oil and simply toast the bread in the toaster. It won’t be as indulgent but still very delicious.
Get all the ingredients together: the toasted/grilled bread, chopped tomatoes, mozzarella, and basil, and avocados.
Mash the avocado on the toasted bread, and add the chopped tomatoes, basil, and mozzarella mix.