Toast the slice of bread. Meanwhile, cut the avocado, scoop out the flesh, mash one half and half of the other, and save the rest for decoration. Add lemon juice, salt, and oil, and mix.

Cover the toast with the avocado mixture. Drain the oil from the tuna and place it on top. Peel the tomato, remove the seeds, leaving only the flesh, cut it into small pieces, and place on top.

Finish by decorating with the reserved avocado slices. Season with salt and pepper, and drizzle with a generous amount of olive oil. And that's it, enjoy a delicious, fresh, and light toast. It's delicious.