INSTRUCTIONS
1. Cook chorizo in Dutch oven over medium heat until browned, 6 to 8 minutes. Using slotted spoon, transfer chorizo to paper towel-lined plate. Cook onion in now-empty pot until softened, about 5 minutes. Add half of greens, broth, sugar, and ½ teaspoon salt. Cover and cook until greens are beginning to wilt, about 1 minute. Stir in remaining greens and cook, covered, stirring occasionally, over medium-low heat until completely tender, about 30 minutes.
2. Remove lid and cook over medium-high heat, stirring occasionally, until liquid is nearly evaporated, about 10 minutes. Stir in chorizo, pimentos, butter, and vinegar and cook until butter is melted, about 30 seconds. Season with salt and pepper to taste. Serve.