How to Make It
In a medium bowl, mash the avocados with the sour cream and lime juice and season with salt.
In a blender, puree the tomatillos with the onion, garlic, cilantro, jalapeños and cumin and season with salt.
Heat the olive oil in a large skillet. Add the turkey and cook over moderate heat, stirring, until no longer pink, about 4 minutes. Add the tomatillo sauce and cook over moderately high heat, stirring, until thickened, 5 minutes.
Wrap the tortillas in a kitchen towel and heat in a microwave oven, about 30 seconds. Lay the tortillas on a work surface. Spoon the filling just below the center of each tortilla, top with a few strips of cheese and roll up as tightly as possible; secure with toothpicks. Brush the tortillas with vegetable oil.
In a large skillet, heat 1 teaspoon of vegetable oil. Add the chimichangas and cook over moderate heat, turning, until golden all over, about 7 minutes. Transfer to plates, top with the mashed avocados and salsa and serve.