Place a rack in middle of oven; preheat to 400°. Using a vegetable peeler, remove zest from 2 large lemons in wide strips, leaving as much white pith behind as possible. Cut lemons in half and squeeze juice into a measuring glass to yield 5 Tbsp.; discard spent lemons. Set lemon juice aside.

Place lemon zest and 1 Tbsp. Diamond Crystal or 1¾ tsp. Morton kosher salt on a large rimmed baking sheet; rub salt into zest aggressively until salt is pale yellow and fragrant. Add 8 garlic cloves, smashed, ¼ cup extra-virgin olive oil, 1 Tbsp. plus 1 tsp. dried oregano, 1 Tbsp. plus 1 tsp. ground coriander, and 1 tsp. crushed red pepper flakes; mix to combine into a paste.

Place 4 skin-on, bone-in chicken thighs (1½–2 lb.) and 1½ lb. fingerling potatoes, scrubbed, halved lengthwise, cut in half crosswise if larger, on baking sheet and toss to coat in paste mixture. Arrange in a single layer, turning chicken skin side up. Roast until potatoes are fork-tender and chicken is crisp, golden brown, and cooked through, 50–60 minutes.

Scoot chicken to one side of baking sheet and spoon potatoes onto a platter. Arrange chicken on top. Pour reserved lemon juice onto baking sheet, stirring with a heatproof rubber spatula or large spoon to scrape up browned bits stuck to baking sheet; pour over chicken and potatoes.

Cut 6 oz. feta into thin slabs or crumble into large pieces and scatter over chicken and potatoes. Top with dill sprigs or parsley leaves with tender stems and season with freshly ground pepper. Serve with lemon wedges for squeezing over.