As far as the red Russian kale goes, it has been good lightly blanched in boiling water and then sautéed in olive oil with onions, garlic, and red pepper flakes. The black Tuscan kale leaves were just too tough for that kind of quick cooking. I decided to cook them the way I cook mature collard greens — long and slow.
Maybe freezing them and then thawing and reheating them at lunchtime would tenderize them. I think it worked. We ate that batch of frozen-and-thawed greens at lunch with some Louisiana-style red beans and rice and a grilled duck breast. The dinosaur kale was pretty good.
Maybe the kale leaves are tough because we've had dry and warm weather for a month or more now, and a lot of bright sunshine. It's even been hot some days. Maybe dinosaur kale will be better in October and November — and beyond — when the plants have enjoyed some cooler weather, more rain, and even some frost.