Heat a saucepan over medium heat and add the vegetable oil. Whisk in the flour and all seasoning ingredients creating a paste like base. Slowly pour in the broth whisking the sauce until smooth. Reduce heat to low and simmer for 10-15 minutes until slightly thickened. Remove from heat. (Note: you can make this sauce a day ahead and simply refrigerate overnight.)
In a bowl, combine the ground venison, ancho chile powder, cumin, coriander, oregano, garlic powder and kosher salt. Using your hands, form 10-12 individual meatballs and set aside on a plate or baking sheet.
Preheat the oven to 400 degrees. Set a 12-14 inch cast iron skillet in the oven to preheat before baking, about 10 minutes.
Carefully place the meatballs in the skillet and drizzle the tops with olive oil. Bake for 20 minutes. Pour the enchilada sauce over the meatballs and top with shredded cheese, chopped green onions and cilantro. Continue baking for 15 minutes until hot and bubbling.
Serve with sour cream and sliced avocado.