Clean and wash the peppers and cut into small strips. Wash and cut the tomatoes into eighths. Peel the cucumber, cut in half and cut into fine slices. Finely chop the onions. Mix together with the drained green beans in a bowl.
Make a marinade with vinegar, water, tuna water and oil. Season to taste with tomato paste, salt, pepper, paprika and sweetener. Finely chop the parsley and fold into the marinade.
Mix the salad with the marinade and let it steep for a moment. Finally, distribute the slightly torn tuna on the salad.
Per serving: 1.1 g fat, 4.4 g protein, 0 bread units.