First heat the dutch oven with ¼ cup of coconut oil or avocado oil. Heat to the smoking point.
Now fry a batch of peppers by laying them on their side into the hot frying oil. Be very careful, splatters are likely and you can get burnt. When the sides are scorched, turn the peppers and scorch all 4 sides this way. It should only take less than a minute per side if your pan is very hot.
Put them aside and cook the next batch of peppers that way until they are all done.
Now add stuffing to the peppers. I like to press it in to firm it a little, but you don't want to push hard. The rice might expand a little as they bake later and the peppers might break apart if you put too much pressure on it.
Next place the peppers back into the dutch oven standing on their bottoms and crowd the pan well so they don't fall over. Fit as many as possible.
Add just a quarter to half cup of water to the bottom of the pot. Place it into the oven and cook on medium or 375℉ until the peppers are soft and well heated through, about an hour.
Your sauce veggies should be getting done before the peppers are. Turn off the heat and use an immersion blender to blend it all smooth. Mine isn't the greatest and will leave some chunks, so I prefer to blend it in a blender, not that chunks are bad, but with this sauce I really prefer it smooth.
Put it all back into the pot and heat it back up to simmer. Turn down the heat to keep it just at or below a simmer to keep it hot till meal time. Just before serving, add the sour cream and adjust the seasonings. It really depends on your taste, how much sour cream you want to add. I like mine creamy, but not too much. So I'd put about half a cup into this amount of sauce. Start with a little and taste it to see if you want to add more.
To serve, I actually like to put some sauce without sour cream on a plate, swirl a little sour cream in it and put a hot pepper on top to serve. Sprinkle it with some parsley, and it will look so pretty.