Cook the potatoes in boiling salted water with their skin on for about 20 minutes. Drain, cool and peel. Cut into thin slices.
Mix orange juice with ¼ teaspoon salt, pepper, mustard and vinegar. Fold in the oil and broth, season to taste and mix the sauce into the still warm potatoes. Let it steep for about 30 minutes.
Wash, clean, sort and spin dry the rocket. Remove stems, cut leaves into strips. Drain the tomatoes, pat dry and cut into strips.
Add the rocket, tomatoes and olives to the potatoes. Mix everything together and serve immediately.