Preheat oven to 350 degrees F. Chop bacon into 1/2-inch chunks and remove sausage from casing if there is one.
Add bacon and sausage to a cold cast iron skillet over medium heat. Cook slowly to brown and render out fat. Once browned, about 10-12 minutes, remove from pan.
Meanwhile, whisk together eggs and greek yogurt. Slice mushrooms and tomatoes, and drain and rinse black beans.
Leave the rendered fat in the cast iron skillet. Add mushrooms and tomatoes and cook until mushrooms are wilted, about 3-4 minutes. Then add black beans and cook for another minute or so.
Add sausage and bacon back to the skillet and try to evenly distribute the fillings over the skillet. Season with salt and pepper.
Pour egg mixture evenly over the ingredients. Return to stove and let heat for 30 seconds. Then transfer to a preheated 350 degree oven and bake until egg is cooked through, roughly 15 minutes.
Garnish frittata with fresh chives, slice, and serve while warm.