Melt the friendly fat in a skillet over medium heat and cook the onion, carrot, and celery with the salt, pepper, thyme, red pepper flakes, and garlic until the veggies are soft, about 5-7 minutes.
In a medium mixing bowl put the ground beef, liver (if using it), egg, sour cream, white rice flour, and the cooked/seasoned veggies and mix well.
Put the meat mixture into a small loaf pan, spread the ketchup on top if using it, and then add the water to the top. Don't leave this out - I know it seems odd but it really makes it so it doesn't dry out! I promise it won't be watery!
Bake the meat loaf uncovered for 1 1/2 hours at 350 degrees. Let the meatloaf rest for 5-10 minutes before cutting.