I often tend to discard the kale stems because I don't want them for the recipe I'm making and can't be bothered to process them or stick them back in the fridge to hang around till I compost them. However, I just made this incredibly recipe and you will be amazed at how good it is. It's the first recipe I have found that I actually like for using kale (and chard) stems. I got the basic recipe from Martha Rose Shulman's Mediterranean Harvest cookbook.
Greens and Tahini Pesto
Ingredients: 2 cups of stems, 1/2 cup tahini, 1/2 cup lemon juice, salt, 1 small onion, or 1 or 2 garlic cloves. In the food processor process the stems and onion or garlic and then add the tahini. I had to drizzle in the lemon juice to get it to come off the sides. Then add salt to taste. Garnish with chopped mint. Serve as a dip or on roasted vegetables. I'm thinking of using this tonight as a topping for sliced roasted beets.