Looks really delish!
But as a short PSA: If you really have high cholesterol, this dish might not be the optimal as the vegan butter and sour cream are high in fat - especially saturated fats. This might bring your cholesterol levels up.
https://www.heartuk.org.uk/low-cholesterol-foods/saturated-fat
If you really need to keep an eye on your cholesterol levels, try not to overdo it with fats in your diet and minimize saturated fats - which are often found in "solid fats" like coconut or palm oil (or any fat derived from an animal source).
You could adapt the recipe quite easily by using a small amount of olive oil to saute the onions & mushrooms. Or you could even go zero-fat by "water sautéing" your ingredients.
The sour cream can be swapped with a "cashew-soymilk-sauce" quite easily. Still has some fat but more on the healty side. And cashews bring a lot of other health nutrients - in contrast to the sour creams.