Preheat oven to 350. Heat the oil in a large heavy oven-safe skillet over medium heat until shimmering. While the oil is heating, pat the chicken dry and season both sides generously with salt.
Cook the chicken skin side down until the skin is golden brown, roughly 8-10 minutes. Flip and cook on the other side for an additional 3 minutes, then transfer the chicken to a plate.
Add the onion to the pan, stirring occasionally to scrape up the brown bits, until golden at the edges, about 8 minutes. Add the stock, zest, juice, juniper berries, and thyme, and then place the chicken back in the pan, skin side up.
Roast in the oven uncovered for about 45 minutes, or until the chicken is cooked through and the skin is crisp. I like to do 40 minutes and then put in under the broiler for the last few to get the skin even crispier. If you do, watch it carefully!
Remove from the oven and take the chicken out of the pan to rest for about 10 minutes before serving. Meanwhile, put the skillet over medium-high heat to reduce the liquid down into a delicious sauce to top the chicken with.
Enjoy!
