Debone each chicken thigh using a sharp knife. Careful not to cut through the chicken thigh.
On a piece of plastic wrap place 1 or 2 chicken thighs skin down. Season each thigh with salt, pepper, and Montreal chicken seasoning.
Place another piece of plastic wrap over the seasoned thighs and beat with a meet mallet until the chicken is about 1/4 inch thick. Once all the chicken is beaten down, set aside.
Rinse the rice a few times with cold water. Place the rice in a saucepan and add enough water to fill about 3-4 inches above the rice.Once the rice comes to a boil, add 1/2 tsp salt and bring the heat down to medium-low. Cook for about 11-12 or until it's almost done.
Strain the rice into a mesh colander and rinse with cold water.
In a skillet, melt butter over medium high heat, add diced onion and sauté until it becomes translucent. Then add in the shredded carrot and cook for another 5 minutes.
In bowl, mix the the rice, sautéed carrot and onion, and garlic.
In the middle of each chicken thigh add about 2-4 tbsp of the rice mixture. Roll each thigh tightly, making sure to keep the rice from coming out of the sides.
Preheat the oven to 370 degrees F. Place each rolled chicken thigh in a 9x13 baking dish and brush the tops of each roll with sour cream.
Cover with foil and bake for 25 minutes. Make sure that the foil is not touching the chicken, it will stick to the chicken and tear the skin. Once 25 minutes go by, remove the foil. At this point there will be a lot of excess oil and liquid in the dish. Drain out some the oil and bake for 25 more minutes. If you want to add a little color, lightly sprinkle the tops with paprika and bake for another 5-6 more minutes.