Preheat the oven to 400°F; position the rack in the lower third of the oven.

Combine potatoes, 2 tablespoons salt, and enough cold water to cover by 1 inch in a large saucepan; bring to a boil over high heat.

Reduce heat to medium; cook, undisturbed, until potatoes are very fork-tender, 25 to 30 minutes. Drain well and pat dry.

Wrap the outside of a 9-inch springform pan with aluminum foil and generously brush the sides and bottom of the pan with 1 ½ tablespoons oil.

Place drained potatoes in an even layer in the pan; using a flat-bottomed measuring cup, smash potatoes firmly into the bottom, then press then over bottom and about 2 to 2 ½ inches up the sides of the pan; the crust should be about ¼ inch thick on bottom and sides.

Use a small offset spatula to evenly spread potatoes, smoothing and patching any holes or thin spots as needed and pushing upper edges into the sides of the pan.

Brush the potato crust evenly with 1 tablespoon oil; sprinkle evenly with 1 teaspoon salt.

Bake the crust until the edges are golden brown and slightly crisp and the center is lightly golden, 35 to 40 minutes.

Meanwhile, trim the zucchini and peel it into ribbons with a vegetable peeler or mandoline, stopping when the seeds appear.

Working with one ribbon at a time, sprinkle ¾ to 1 teaspoon of feta along the length of the zucchini; starting from the short end, roll up semi-tightly. Repeat with the remaining zucchini and feta.

Whisk together eggs, cream, dill, oregano, lemon zest, garlic powder, and remaining 1 ½ teaspoons salt in a large bowl until well combined, about 30 seconds.

Arrange zucchini rolls upright in the prepared crust. Pour the egg mixture over the filling.

Carefully transfer the quiche to the oven.

Bake until the filling is set and a paring knife inserted into the center comes out clean, 50 to 55 minutes, loosely covering the edges with aluminum foil to prevent overbrowning, if needed.

Let cool slightly on a wire rack before serving, about 20 minutes. Serve garnished with more dill and oregano.