Put the potatoes into a pan of cold water and bring to the boil. Simmer for about 15 minutes until tender then add the onion for a minute and drain.
Cut the potatoes in half and put them in a bowl. Drizzle with the oil, lemon juice and honey, Season with salt and combine.
Cut the beetroot and radish into small chunks, add these to the salad.
Mix the yoghurt with the mustard and honey and pour this over the salad.
Slice the chilli thinly, add to the salad (if used).
Mix everything together. Taste and adjust the seasoning to your liking.
Just before serving, scatter some fresh herbs on the top.