Pour oil into a pan and on high heat start searing the rabbit. Once one side is getting some golden brown crust sprinkle parsley and half of the salt on top and flip it over.
Once the other side of the meat is getting a golden brown crust stir in the diced onion with the other half of the salt.
Fry the onion under the meat while stirring it until at least it gets a translucent, glassy look. It takes about 5 minutes on high heat. If we are after a bit sweeter flavor then we can cook it longer on low heat until it gets a brownish caramelized look but this takes at least 15 minutes.
Add black pepper, rosemary then pour a cup of water into the pan place a lid on and bring it to boil. Lower the heat and simmer for about 40 minutes.
Carrot Sauce
Heat up oil to medium to high heat and fry onions until glassy / translucent look for about 5 minutes.
Add the carrots and saute for 5 more minutes on high heat then lower the temperature to low and stir-fry until it starts to caramelize for about 10 - 15 minutes. Stir it frequently as it could burn down badly spoiling the sweet sauce with a bitter burnt taste.
When the onion gets a brownish caramelized look pour the mixture into a big bowl add the sour cream and mix it together. If it feels too thick add some liquid from the stew or water. Some like to mix the whole carrot sauce with the stew making a creamy rabbit stew.