We don't have a problem with eating greens. I've always steamed and salted them like you and then squeeze lemon juice over them. Yum! I do not cook kale. I use it in our green smoothies each morning and I also make a Wilted Kale Salad that we think is delicious. Our favorite greens for cooking are Spinach, Beet tops, and Swiss chard. I wish I could develop a taste for Mustard greens but haven't so far.
For our green smoothies I use, Spinach, kale, Swiss chard, Orach, Sorrel, beet tops, New Zealand Spinach, with a tablespoon of Chia seeds thrown in. These aren't used all at once. I only use about 2 or 3 different greens at a time but always use the Chia seeds. Flax works good too.
I'm interested in sauces to replace margarine on our cooked vegetables. Yes, I also remember reading that Ellen used cream to make her food more tasty which I know she wouldn't do now if she were living. So I want to try your sauce on my vegetables.
You mentioned potato powder. Where do you get that? I have seen potato flour. I wonder if that would be the same.