Boil the potatoes in their skins and let cool down well. Peel the potatoes, cut in half lengthways and cut across into 4mm thick slices. Wash the cucumber and radish, cap at both ends, peel and cut or slice across into 3mm thick slices.
Wash the carrot, cap both ends and peel. Cut about 4cm from above and cut lengthways into thin slices and cut them into strips. Cut the strips crosswise into small cubes. Peel the peppers, wash them, cut in half lengthways, unfold, core and cut the halves into cubes like the carrot. Halve the vegetable onion lengthways. Cap one half at both ends, peel and cut into very small pieces.
Wash the celery, pluck the leaves and chop finely. Cut the stalks crosswise into small rolls and freeze. Cut the orange peel into very small pieces.
Lightly brown the onion pieces with 2 tablespoons of the olive oil. Mix together with the oil and the remaining vegetables in a bowl. For the dressing, dissolve the chicken stock in the orange juice and mix in the remaining ingredients. Optionally, squeeze the garlic clove and mix with it.
Pour the dressing over the salad, mix gently and let steep for about 30 minutes. Before serving, mix in the remaining olive oil, garnish and serve at room temperature as a starter or side dish.