Cut the spring onions into fine rings, core the beefsteak tomatoes and dice them finely. Place in a bowl with the chickpeas and tuna.
Make a dressing from mustard, sugar, vinegar, oil, cream, salt and pepper and add the finely chopped garlic and chopped parsley. Mix the dressing with the remaining ingredients and let it steep for a while.
As a vegetarian salad it is also very tasty, then just leave out the tuna.