Place buckwheat, cranberries, water, and salt into the Instant Pot.
Close the lid. Select PRESSURE COOK and set the pot at high pressure for 15 minutes. At the end of the cooking time, allow the pot to rest undisturbed for 10 minutes and then release all remaining pressure.
Meanwhile, place kale, olive oil, salt, and orange zest in a large mixing bowl. Using your clean hands, mix together the ingredients, mashing and macerating the kale as you go. This will help soften the kale, reduce some of the bitterness, and allow the seasonings to penetrate.
When the buckwheat is cooked, fluff up the grains with a fork.
Divide kale into four for a main course or 6 plates for a side dish. Place the kasha on top of the kale, and top with walnuts before serving. Or do what I do, which is mix everything into one big bowl and serve.