Heat a pan with a few inches water over medium heat. Bring to a boil, season with salt, to taste, and add the bitter greens. Cook for a few minutes, then drain and reserve.
Heat the extra-virgin olive oil in a large skillet over medium to medium-high heat and add the andouille. Brown the crumbles or the chopped cooked sausage, then add the onions and cook until softened, about 5 minutes. Stir in the stock and add the bitter greens. Heat through for a few minutes, then douse with vinegar, and season with sugar, salt, pepper and nutmeg, to taste. Transfer to a serving bowl and serve.