Place potatoes in a large pot and fill with enough water to cover them. Add 1 tablespoon salt. Bring to a boil, then reduce heat to medium-low. Cook for 15-20 minutes, until potatoes are cooked, but not too soft. Drain potatoes. Let them cook down. Peel potatoes, if you'd like.
Slice potatoes into ½ inch rounds. Season with salt and pepper to taste. Brush or spray with vegetable oil.
Prepare a ribbed skillet, spray lightly with vegetable oil. Heat skillet to medium heat.
Grill potatoes for 4-5 minutes per side, until browned, turning once. (Alternatively grill potatoes on the grill).
Feta Dressing
Add all ingredients for the dressing in a bowl and whisk to combine.
Notes
Place mixed greens on the bottom of a large plate. Add potatoes over it (they should not be too-hot!). Pour dressing on top. Garnish with chopped scallions and parsley.