Preheat your oven to 425 degrees, with the oven rack in the middle position

For the chicken

1. Place the chicken thighs on a large plate, skin-side down, and season the flesh side of the chicken with kosher salt, black pepper, a basically all-purpose seasoning. I used Sazon Complete (a blend of all the typicals, herbs, garlic, onion, etc). Let it sit for 30 minutes at room temperature to allow the seasoning to do it’s job.
2. After 30 minutes, arrange each thigh in a COLD 12-inch skillet, skin-side down. Make sure each thigh has proper contact with the bottom of them pan. When ready, set the skillet over medium heat and slowly allow the skin to render. This will take about 8-10min. When the chicken easily releases and is golden brown, turn each thigh over to sear on the flesh side for just one minute. Transfer the chicken back to the plate to rest, crispy skin-side up. do not cover/tent. Don’t worry, the chicken isn’t fully cooked anyway, so we’re not cross-contaminating. 
3. Depending on how you seasoned the chicken, you may or may not have a lot of really dark fond at the bottom of your skillet. Pour off all but 1-2 tablespoons of the rendered chicken fat, then clean the skillet out if the fond is very dark. Normally we keep fond, but because we don’t want it to muddy up our curry, nor do we want it greasy, it’s fine to rinse it out. 

For the Green Coconut Curry sauce

1. Bring the now clean skillet back to the stove and melt 2 tablespoons of butter plus the saved rendered chicken fat over medium heat.  
2. Add the sweet potatoes along with a pinch of salt. Toss to coat the potatoes in the butter and chicken fat and gently sauté them for about 5 minutes, or until just the edges of the potatoes begin to soften. Adjust your heat throughout this process as needed. We’re not looking to color the sweet potatoes, just soften their edges.
3. Add the leeks, plus a pinch of salt, and saute for about 3 minutes just until they start to soften.
4. Stir in the ginger and garlic until fragrant, about 30 seconds.
5. Add the kale and swiss chard and gently toss everything to combine and help the greens wilt. If you need to add a little more butter/chicken fat/oil, do so. Cook the greens until they wilt, about 3-5 minutes. 
6. Add half (2 ounces) of the the green curry paste and stir until fully combined, allowing the paste to cook out slightly for about 2 to 3 minutes. 
7. Gently pour in the coconut milk and stock of choice (or water). Stir until everything is incorporated and bring to a gentle simmer, still over medium heat. 
8. As soon as the mixture starts to simmer, add the fish sauce, some of the brown sugar (start with a large pinch), and lime juice. Taste for salt! Adjust the salt and brown sugar to your liking, but keep in mind that this should not be sweet. The brown sugar is added to balance all the savory and spicy flavors.
9. Simmer the mixture for about 7-8 minutes over medium heat, then taste again. If you want to add the remaining half of the green curry paste, do so.
10. When the greens are starting to get tender, stir in the fresh basil. Now add the chicken to the sauce (along with accumulated chicken juices) skin-side up, making sure the chicken skin isn’t submerged. It should be directly above the sauce line. If there’s too much liquid in your skillet, spoon some of it out. Also, if there isn’t enough liquid, add more! 
11. Once the chicken is arranged onto the sauce, turn off the stove and immediately place the skillet on the middle rack of your preheated oven to finish cooking for about 20-22 minutes, or until the chicken registers 185-190 degrees internally on an instant-read thermometer.
12. Carefully remove the skillet from the oven and immediately garnish with fresh lime zest, lime juice, and more basil. 
13. Allow the dish to rest for 5 minutes before serving. Enjoy.