Finely chop all the onions (spring onion and yellow), heat the butter (can be replaced with olive oil) in a small pot, add the onion, cover and allow to soften on very low heat
Chop the potatoes, add over the onions, add the vegetable stock and boil on low heat for about 30 minutes.
Using a vertical blender cream everything, add white pepper and salt to taste
Remove from heat, let it cool a little bit, add the light cream and lemon juice, then garnish with chives and serve.