Heat oil in a large cast-iron or heavy-bottom skillet over medium heat.
Sauté the onion and jalapeno in the butter until softened.
Add flour and cook, stirring, for about 1 minute.
Stir in garlic and cook for another 30 seconds.
Whisk in salsa verde, heavy cream, and chicken broth, smoothing out any lumps.
Continue cooking for about 5 minutes, or until the sauce thickens enough to coat the back of a spoon. If too thin, cook longer until reduced; if too thick, add water ¼ cup at a time until the desired consistency is reached.
Add 2 teaspoons of Adobo seasoning, salt, pepper, and cumin to taste.
Remove from heat and stir in sour cream and ¼ cups cilantro.