Greens saut'e

Ingredients:

1/4 cup extra-virgin olive oil
1 cup thinly sliced shallots
2 garlic cloves, crushed
1 tsp crushed red pepper flakes
1 3/4 lb assorted greens like kale and swiss chard. stems removed and thinly sliced, leaves chopped
1/4 cup apple cider vinegar
3 tbsp unsalted butter
kosher salt and ground pepper

Preparations:

Heat oil in a large pot over medium heat.  Add shallots and garlic.  Cook, stirring often until soft, about 5 minutes.  Add red pepper flakes: stir 1 minute.  Add kale stems and saute for like 4 minutes.  Add leaves and cook, tossing often, until crip-tender, about 5 minutes. Stir in vinegar.  Add butter; toss until melted.  Season with salt and pepper.