Rinse the lentils and cook them in salted water for about 30 minutes, then drain and let them cool. Cut the Tropea onion into julienne strips and leave it to soak for a couple of hours. Peel and dice the cucumber; wash and dice the cherry tomatoes. Put the bread in a large bowl, sprinkle it with a little water, and add the legumes and chopped vegetables; season to taste with salt, extra-virgin olive oil, white wine vinegar, and oregano.