Quarter the potatoes and keep the skins intact. Add them to a pot of salted water. Cover and bring to a boil. Uncover and simmer for about 6-9 minutes, or until fork tender.
Meanwhile, chop the red onion, garlic, and juice and zest the lemon.
Strain the potatoes and let them cool. To speed up this process, spread them on a sheet pan.
When the potatoes have cooled, mix the créme fraîche, olive oil, garlic lemon zest and juice. If you don't have créme fraîche, substitute with a mixture of half cream cheese and half sour cream or greek yogurt. Season with salt and pepper.
Place the potatoes in a bowl and mix the créme fraîche mixture with the potatoes. Top with capers and kale or swiss chard. Adjust the seasoning if need be.
Keep in the fridge until ready to serve.