Rinse green beans, trim and cut into 4 cm (approximately 1 1/2 inch) long pieces. Cook beans for 8-10 minutes in a pot of boiling salted water, then drain, rinse with cold water and drain again.
Scrub potatoes and cut in half if required. Rinse tomatoes and cut in half.
Drain anchovies and let dry.
Rinse lettuce leaves, shake dry and tear into small pieces.
Mix white vinegar in a bowl with balsamic vinegar and olive oil and season to taste with salt and pepper.
Mix all salad ingredients in a large bowl with the vinagrette and serve garnished with caperberries and olives.