Set poblanos on a foil-lined baking sheet. Roast under the broiler until skin is charred, then turn and repeat for the other side.
Remove chiles and immediately place in a sealed plastic bag to steam. Reduce oven to 350°.
While poblanos are cooling, cook turkey in a large skillet over medium-high heat. When turkey is browned, add black beans, tomatoes, & onions. Cook until onions are translucent.
Remove skillet from heat. Fold in queso fresco & olives.
Carefully peel blackened skins off of chiles, leaving the stems intact. Cut a slit in one side.
Stuff each chile with the turkey mixture and place cut-down in a greased baking pan, p. Pour enchilada sauce evenly over the top.
Bake at 350° for 20 minutes, until sauce is bubbling.
Top with avocado slices, sour cream, & green onions and serve hot.