Christensen's vinegary, buttery, barely cooked greens stay bright in color and flavor.

Yield: Makes 8 servings
Active Time: 30 minutes
Total Time: 30 minutes

1/4 cup extra-virgin olive oil
1 cup thinly sliced shallots
2 garlic cloves, crushed
1 teaspoon crushed red pepper flakes
1 3/4 pounds assorted greens (such as kale and Swiss chard), stems removed and thinly sliced, leaves chopped
1/4 cup apple cider vinegar
3 tablespoons unsalted butter
Kosher salt, freshly ground pepper

Heat oil in a large heavy 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; sauté for 4 minutes. Add leaves and cook, tossing often, until crisp-tender, about 5 minutes. Stir in apple cider vinegar. Add butter; toss until melted. Season to taste with salt and pepper.