In a large dutch oven or soup pot, saute the onions and garlic in the olive oil and a pinch of red pepper flake until softened and beginning to change color.
Add the broth and the sliced potatoes.
Bring to a simmer and cook the potatoes until softened, about 15 minutes. Use a spoon or potato masher to break the potatoes up into smaller chunks.
Stir in the greens, work in batches and add more as they wilt.
Add the chorizo and/or optional ingredients and cook until heated through.
Taste and adjust the seasoning.