Season the chicken on all sides with salt. Heat a large oven-safe pan over medium heat and add a bit of avocado oil to prevent sticking. Add the chicken, skin side down and cook, pressing to ensure good contact with the pan. Cook until the skin is golden and crisp. Transfer, skin side up to a plate and set aside (it will be added to the dish and fully cooked later). Do not clean the pan.
Remove all but one tablespoon of oil from the pan. Add the onion and celery and cook, stirring occasionally until the onions are soft and translucent, about 5 minutes. Add the mushrooms and a pinch of salt. Cook, stirring occasionally until the mushrooms release their liquid and the liquid is evaporated, about 5-10 minutes more.
Add the garlic, thyme, and bay leaves. Cook, stirring constantly until fragrant, one minute more. Add the tomato paste and cook for 2 minutes (helps to remove the tinned flavor). When the tomato paste starts sticking to the pan, add the brandy and cook until no liquid remains. Then add the wine and cook until the liquid is reduced by half. Stir in the chicken stock, gelatin, coconut aminos, tomatoes, tarragon, and parsley.
Remove from heat and add the chicken back, skin side up, nestling it into the stew (you want the skin to stay above the liquid so it stays crisp). Transfer to the oven and cook for 30 to 40 minutes at 400ºF.
Remove chicken and reduce the sauce, if needed until there is little liquid left. Serve with chicken.