Rinse the rice a few times and place it in a saucepan. Add enough water so that there is about 4 inches of water above the rice. Bring the rice to a boil and cook on medium high heat for 11 minutes. Once the rice is about 90 percent done, strain the water and set aside.
Cut out the core off the cabbage and chop the rest of the cabbage into tiny little pieces. Add the finely chopped cabbage into a large bowl of boiling water and let it sit for 2 minutes. Then, strain the water and rinse with cold water so that the cabbage stops cooking.
In a skillet heat oil to medium high heat and cook 1/2 cup chopped onion and 2 shredded carrots. Cook until the onion becomes translucent.
In a large bowl mix the ground chicken, cabbage, rice, salt and pepper, with the sautéed onion and carrot. I find it easiest to just mix it with my hands.
Using a cookie scoop, scrape out balls of the mixture. Make sure each scoop is very full. Round each ball in your hands so that its more compact. In a 9x13 baking dish tightly place the cabbage rolls.
Preheat your oven to 370 degrees F.
In a skillet heat 3 tbsp olive oil and sauté rest of the onion and carrots. Once the onion is translucent add in the sour cream and tomato sauce. After about 5 minutes, stir in 1/2 cup water.
Spread the sautéed mixture over the cabbage rolls, cover with foil, and bake for 1 hour.