Drain the tuna. In the meantime, wash the cucumber and cherry tomatoes well. Cut the cucumber into small (about 0.5 cm) cubes (if you like it, you can scrape out the inside of the cucumber with a spoon beforehand). Halve or quarter the cocktail tomatoes, depending on their size, so that they match the size of the cucumber pieces.
Place the cucumber and tomato pieces in a salad bowl. Cut the onion into very small cubes and add to the cucumber and tomatoes. Now add the tuna and mix everything well. Mix with the yogurt sauce and season with herbs from Provence. Finally, season everything with salt and pepper to taste.
Tip: The salad can also be expanded as desired, depending on what is still in the refrigerator. Corn, pepper pieces or spring onions also go well with it.