Pat the chicken dry. Use paper towels to dry the thighs thoroughly. Dry skin equals crisp skin. Trim any excess fat if needed.
Mix the marinade. In a large bowl, combine the lemon zest, lemon juice (about 1/4 cup), minced garlic, olive oil, chopped thyme/rosemary, paprika, a pinch of red pepper flakes if using, honey, 1.5 teaspoons kosher salt, and 1 teaspoon black pepper.
Coat the chicken. Add the thighs to the bowl and toss until evenly coated, making sure some marinade gets under the skin.
Let sit 30 minutes at room temperature, or cover and refrigerate up to 12 hours.
Preheat the oven. Set to 425°F (220°C). Place a rack in the center. Line a sheet pan with foil or parchment for easier cleanup.
If you have a wire rack, place it over the sheet pan for extra crisping.
Arrange on the pan. Place thighs skin-side up with space between them. Tuck a few lemon slices and herb sprigs around the chicken. If adding potatoes or onions, toss them with a little oil and salt, then spread around the thighs.
Roast until golden and crisp. Cook 35 to 45 minutes, depending on size.
The skin should be deep golden, and the internal temperature should reach 175°F to 195°F in the thickest part for tender, pull-apart results. Dark meat gets more tender above 175°F.
Broil for extra crispness (optional). If the skin isn’t as crisp as you’d like, broil for 1 to 2 minutes. Watch closely to avoid burning.
Rest and finish. Let the chicken rest 5 to 10 minutes.
Sprinkle with chopped parsley and a final squeeze of lemon for brightness. Spoon pan juices over the thighs before serving.
Serve with simple sides. Good pairings: garlic mashed potatoes, buttered rice, couscous, quinoa, or a crisp green salad. A side of roasted carrots or asparagus also works well.