For the pesto: Blanch (dip for 10 seconds in boiling, salted water then transfer to an ice-cold bath) the radish leaves and ½ cup parsley, drain, pat dry on a paper towel and roughly chop.  In a mini-food processor or mini-blender, combine the greens, pickled garlic, pistachios and lemon juice.  Pulse and slowly add the olive oil until it becomes a smooth paste.  Add  about 2 tablespoons (or more) of water if necessary, for a smoother flow.  Season with salt and pepper.

For the yogurt: In a large colander, place the yogurt in a double-layered cheese cloth. Wrap it and make a knot at the tip and suspend it over the colander using chopsticks. The colander is not essential but is quite convenient if the knot breaks, so you can gather the yogurt again in the cheese cloth without starting over. Let it sit for about an hour. Drain as much whey as possible.

Boiling the potatoes: Wash the potatoes. Place them in a pot; fill it with cold water until the potatoes are barely covered. Bring to a boil; add salt and reduce the heat to medium-high. As soon as the water boils, cook for 20 minutes until slightly tender but still firm.  Drain the potatoes and let them cool a little. Season with salt. Add the pesto. Toss until well coated.

Assembly time: When you're ready to serve, add red onions and yogurt. Mix well and garnish with more parsley.

Bon appétit!