Melt the butter in a 6-quart pot over medium heat. Add the cardamom, fenugreek and nigella seeds and cook, stirring often, 1 to 2 minutes. Increase the heat to medium high, pour in the oil and cook the onions, stirring often, until browned, about 10 minutes. Add the garlic, chiles and ginger and cook, stirring often, 3 minutes longer.
Stir in the collard greens, sprinkle with some salt and black pepper and pour in 1 1/3 cups water. Cover and bring to a boil, and then reduce the heat to a simmer and cook, stirring occasionally, until the collards are tender, 50 to 55 minutes. Stir in vinegar to taste and serve the collards hot.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.