In a Dutch oven, heat olive oil over medium-high heat, one turn of the pan. Add chicken, season with salt and pepper and brown on each side; remove to plate. Add onions and garlic, and reduce heat a bit. Cook to soften onions, 12-15 minutes. Add paprika and cayenne or hot paprika, and stir 1 minute; add stock and bring to low boil. Add chicken back into the pot and partially cover. Simmer at a low boil 12-15 minutes more. Remove chicken to a plate, raise heat and reduce liquid 3-5 minutes.
Meanwhile, place potatoes in pot cover with cold water bring to boil, salt water and cook potatoes to tender. Drain potatoes.
Just before serving, stir crème fraiche and lemon juice into the chicken. Arrange chicken and potatoes on dinner plates, douse with sauce and finish with chopped chives, dill and parsley.
For the Brine:
Bring 2 quarts water to a boil with the salt, light brown sugar, peppercorns and bay. Dissolve salt and sugar then remove from heat and add lemon juice. Add an equal amount of ice to the liquid to quick-cool the brine. Place 1 or 2 spatchcocked (backbone removed) chickens, a whole 3-pound chicken or 4 pieces of split breasts and/or 4 dark meat quarters (leg and thigh attached) in a 2-gallon bag plastic food storage bag with zip top, add the brine and close the bag, letting out any excess air. Store in lowest part of the refrigerator overnight or up to 2 days.