Preheat oven to 450.
1. Break down chicken into 8 pieces and season chicken with salt. Heat a large, heavy ovenproof skillet (preferably cast iron) over medium-high heat. Swirl in oil. Cook chicken, skin side down, until browned, about 5 minutes. Flip chicken, and push to side of skillet.
2. Add garlic and onion and sauté till golden. Add potatoes, tomato paste and season with salt. Add water to pan. Bring to a boil. Add tarragon to liquid. Return to a boil, then lower heat to a high simmer.
3. Cook until potatoes are tender and chicken is cooked through, about 30-40 minutes. Serve immediately.
In my opinon: This was really good. I hope you have a BIG skillet, this was hard to squeeze in. Also, the directions never say to put it in the oven so we didn't. I guess you could assume that step 3 is to place this in the oven.