In standard skillet, sautée sliced mushrooms (amount as to your preference) and onions in olive oil, with some ground pepper, until onions begin to caramelize, browning around the edges. Turn heat to low, or remove from heat altogether, pile as much chopped kale on top as will fit, cover and let simmer or just steam for about five minutes.
Eat.
One hint, with the kale, just use the leaves, trimmed off the stem. Stems tend to be pretty tough. Overall, I find kale an excellent substitute for spinach in anything cooked, as it doesn't get mushy the way spinach does. And it is generally inexpensive and highly nutritious. I routinely grow kale in my garden; it's dead easy to grow, and is the most frost-resistant vegetable imaginable. I've picked it as late as November here in Alaska, with snow on it.
Addendum: You can do this recipe with swiss chard or beet greens pretty well, too.
caw