Pour flageolets and corn into a sieve, rinse and drain. Drain the olives, cut in half. Boil up the vegetable stock. Stir in vinegar, salt, pepper and oil. Swivel the corn and flageolets in it and fold in the olives. Let the salad stand for at least 30 minutes and season again.
Wash parsley, dab dry and, except for something to garnish, pluck off leaves, chop coarsely and fold into the salad. Wash, clean and slice the tomatoes. Cut feta cheese into slices. Arrange tomatoes, feta cheese and salad on plates. Garnish with the remaining parsley