1 Tbsp. minced garlic
1/2 tsp. sea salt
1/4 tsp freshly ground black pepper
2 tsp. minced fresh rosemary
1/4 tsp red pepper flakes
2 Tbsp. fresh lemon juice
3 Tbsp. extra-virgin olive oil
4 bone-in, skin-on chicken thighs, trimmed
2 large lemons, cut crosswise into 1/4 inch thick rounds, seeded
Vegetable oil, for brushing lemons
To a medium bowl, add garlic, salt, pepper, rosemary, pepper flakes, lemon juice, and olive oil; whisk to combine. Add chicken and toss to coat. Cover and refrigerate to marinate for at least 30 minutes or up to 2 hours.
Preheat oven to 450° Preheat a grill or grill pan over medium-high heat. Remove the chicken from the marinade, pat dry with paper towels, season with salt and pepper, and place on the grill, skin side down. Flatten the chicken with a brick wrapped in aluminum foil or a grill weight. Cook until skin is crispy, about 8 minutes. Remove the brick and turn the chicken skin side up. Transfer chicken to a small, rimmed baking sheet and transfer to the oven to finish cooking; an instant-read thermometer inserted in the thickest part of the chicken will register 165°, about 20 minutes.
Wipe out the grill pan, if using, and heat the grill pan or grill over medium-high heat. Using a silicone brush, lightly brush the lemon slices with vegetable oil and grill until grill marks develop, about 2 minutes per side.
To serve: Transfer chicken to a serving platter and serve with grilled lemon rounds on the side.