Heat the oven to 425°F. Line a large rimmed baking sheet with parchment, or lightly oil the sheet if preferred.

Place the potatoes in a saucepan and cover them with cold water. Add 1 1/2 teaspoons kosher salt, bring the water to a boil, and cook for 15–20 minutes, until the potatoes are fork-tender.

Drain the potatoes thoroughly and let them steam-dry for several minutes. This removes surface moisture and helps the potatoes brown rather than steam in the oven.

Arrange the potatoes on the prepared baking sheet with space between them. Use the bottom of a glass or measuring cup to press each potato to about 1/2-inch thick without flattening it completely.

Stir together the olive oil, garlic, and black pepper. Spoon or brush the mixture over the potatoes, coating their tops and the exposed pan around them.

Roast for 25–35 minutes, turning once if necessary, until the edges are deeply golden and crisp. For additional browning, broil for 1–2 minutes at the end while watching closely.

Sprinkle the hot potatoes with feta, parsley, dill, lemon juice, and lemon zest. Taste and add additional kosher salt if needed, then serve immediately.