Pat the chicken thighs dry with paper towels to ensure crispy skin, then season generously with salt and pepper on both sides.
Heat the cast-iron skillet over medium-high heat until shimmering, then add the olive oil and swirl to coat the bottom evenly.
Place the chicken thighs skin-side down in the hot skillet. Cook without moving for about 6-8 minutes, until the skin turns deep golden brown and crispy, and you hear a satisfying crackling sound.
Flip the chicken thighs using tongs, then add the minced garlic and herbs around the chicken if using. Cook for another 8-10 minutes, reducing the heat slightly, until the internal temperature reaches 75°C (165°F) and the juices run clear.
Squeeze fresh lemon juice over the chicken during the last 2 minutes of cooking, allowing it to bubble and mingle with the garlic and drippings, creating a fragrant sauce.
Remove the chicken from the skillet to a plate and let it rest for 5 minutes, allowing the juices to redistribute and keep the meat juicy.
While the chicken rests, tilt the skillet slightly and scrape up any browned bits, then add a splash of water or broth to make a quick pan sauce. Stir to combine and heat until bubbling.
Spoon the lemon-garlic sauce over the rested chicken and serve immediately, garnished with extra lemon wedges or herbs if desired.