Bake and Prepare the Potato Skins: Place one rack in the center of your oven and another rack in the top half of the oven (roughly 4 to 5 inches below your broiler). Preheat the oven to 400°F (204°C). Line a half sheet pan with aluminum foil.
Place the potatoes in a medium mixing bowl. Toss the potatoes with one tablespoon of extra olive oil and sprinkle with kosher salt and pepper. Distribute the potatoes evenly in rows on the sheet pan – so they are not touching one another. Bake on the center-rack for 25 to 30 minutes, or until a wooden skewer can easily be pierced through them without meeting resistance.
Set on a cooling rack until the potatoes are cool enough to handle. Increase the oven temperature to 425°F (220°C). Slice the potatoes in half lengthwise. Hold each potato half in the palm of one hand and using your other hand, carefully (note: red potatoes have more delicate skin than russet potatoes) scoop out the potato flesh with a small melon ball scoop or spoon leaving about ⅛-inch of potato in each skin. Set the scooped potato into the mixing bowl from earlier – and use for mashed potatoes or store other cooking applications.
Set a rack in the foil-lined sheet pan. Brush the potatoes with olive oil, inside and out, and sprinkle lighting with salt. Distribute the skins, skin-side up, on the rack and bake for 8 to 12 minutes, gently flipping the potatos halfway through.
Assembly: Preheat the oven broiler to the highest setting. Combine the diced tomato and cucumber in a small bowl and season with salt and pepper, set aside for later. Spoon between 1 to 2 teaspoons of the olive tapenade hummus into each potato skin - so they are roughly half way full. Top with a small amount of crumbled feta. Set the potato skins back on the rack lined sheet pan. Broil in the top third of the oven (4 to 5 inches below your broiler) for 3 to 4 minutes, watching carefully, until the feta is lightly caramelized and the hummus is warm.
Remove and top each potato skin with a small spoonful of the chopped cucumber and tomato mixture. Garnish with sliced scallions. Serve immediately.
These potato skins can be made vegan or dairy-free by simply leaving out the feta cheese. Or you can simply set aside a few potato skins without cheese for friends and family!