Boil all the vegetables whole and unpeeled - the potatoes and carrots in one pot and the beetroots in another - until they are just tender or easily pierced with a knife. Drain, cool and remove the skins. Dice and place in large bowl.
Dice the pickles and add to the bowl then drizzle oil and vinegar over the mixture. Chop the spring onions and add to the salad. Add salt to taste, mix all together and chill.
Beetroots colour everything red!
...so if you want the other vegetables to retain their colour put the beetroots in a separate bowl after cooking, peeling and chopping and then mix in the dressing with them in that bowl. Then carefully fold them in with the rest of the salad.